You almost refer to the constitution as if it is a document form the deep past. The constitution can be amended and has been several times. This means it is current and representative of peoples current will (- whatever time it takes to make changes into effect). You could be better of arguing that if something that is constitutional shouldn't be followed it should be made unconstitutional rather than stop following the constitution.
Now it could be a valid line of criticism that in the maintenance of the constitution too much emphasis is placed on the original intents and purposes. But mainly the constitution has been so stable because Americans have kept finding the principles good. If somebody would come and suggest that this liberty thing be taken off from constitution that kind of modification would be unlikely to pass. Other kinds of revisions such as cleaning it from religious references might be more successful (thought I doubt that one).
Disregarding sovereignty of legal entities in favor of ethical considerations very easily takes the form of warmongering where you do crusades to impose your brand of morals. It is like saying that rogue states ought to be bulldozed over. It is a little more understandable when you mean things like Iran with rogue states but when you mean states of your own federation it is remarkably militant. Well, it did end up starting a war. But appeals to constitution are attempts on how it could have been processed without war.
Note that in arguing that sovereignty of states should not be recognized you are warmongering for a war that hasn't been fought yet (if you are not arguing that the states should hand over sovereignty voluntarily, unilaterally declaring that they don't have it anymore is taking it away from them by force).
It can be kinda dodgy that amendments to the constitution are not made as often as maybe they should be and that there is undue pressure to keep the legal practice current via interpretation of law. However that existence of the constitution makes a different impact in different times doesn't by itself tell of a design flaw. If not in the constitution it is a popular ideas that Americans should be judged by a "jury of their peers". This kind of declaration might lead in a changing sense of justice among ordinary people to give different judgements at different points in time. However it can also be seen to protect american from old dated world views. Inclusion of ordinary people ensures that legal professionals do not stray too far form the realities of everyday life or that old dated worldviews would give unjust results in a new world. Now I am not super thrilled how the situation of application of a law that should have been updated is handled. Ordinary people get a veto right against all the honed intricacies of law machinery. While the attempt to try to have politically motivated supreme court decisions is apparent and a little problematic there is an even bigger problem that anyone that is eligible for jury duty can try to spit on laws that are less powerful than the constitution, gaining a power comparable to that of a supreme court judge. Arguably if your legal system can have the effect of placing a duty to cause a death of a person (capital punishment) it does need pretty heavy duty freedom of conscience. However when the power is so much that showing awareness of it can make you ineligible for jury duty there is a paradoxical situation where citizens can't be informed of their constitutional guarantees so that persons that use them in appropriate situations do not get overshadowed by persons that use them for politically motivated reasons. Paradoxically if you understand what the constitution does for you, you can't exercise all its rights (I am not super clear whether every US citizen that reads this has lost part of their constitutional rights, people that know better please inform whether I should retract better).
Unlike some courts of US, The US supreme court is, like it's name, supreme. It is the final authority on the application of US law. It's decisions by definition can't be unconstitutional. If it makes a mistake it must correct itself. Off course the supreme court is free to consult the general public on whether it should make such a correction. But there is none that can compel it in a hard way to make such a decision (you need to bring down all of US law to do it, ie russia with it's nukes is your best chance of forcing the issue, or "The people" need to withdraw their mandate for which there is no formal process and the informal process is usually called a revolution). In case that there is sufficient difference between the law makers and law interpreters, the law makers must make a new law that is sufficiently clear that it can't be interpreted in the "wrong way" (or like end the separation of powers and abolish the supreme court). However because retroactive laws are forbidden (atleast of now) those particular cases heard can't be recovered from (off course you can make laws that make it mandatory to make up past US conduct to particular individuals, but it is kinda bad style of legislation to mention people by name).
Things like same-sex marriage are probably not important enough to bring down the federation of USA down (I guess slavery was?). The issue is how Americans can tackle those issues without trampling with the constructions that keep their country standing. If you mainly care about marriage arrangements you need to show an alternative way how the mechanism that keep interfering can be solved in another way that they don't interfere with marriage issues. Just throwing stuff to the waste bin is not a solution.
I am sure the majority of the discussion surrounding the Unites States recent Supreme Court ruling will be on the topic of same-sex marriage and marriage equality. And while there is a lot of good discussion to be had, I thought I would take the opportunity to bring up another topic that seems often to be glossed over, but is yet very important to the discussion. That is the idea in the USA of praising the United States Constitution and holding it to an often unquestioning level of devotion.
Before I really get going I would like to take a quick moment to say I do support the US Constitution and think it is important to have a very strong document that provides rights for the people and guidelines for government. The entire structure of the government is defined by the Constitution, and some form of constitution or charter is necessary for the establishment of any type of governing body. Also, in the arguments I use as examples I am not in any way saying which side I am on. I am simply using them as examples, and no attempt should be made to infer my political stances from how I treat the arguments themselves.
But now the other way. I often hear in political discussions people, particularly Libertarians, trying to tie their position back to being based on the Constitution. The buck stops there. The Constitution says it, therefore it must be right. End of discussion. To me this often sounds eerily similar to arguing the semantics of a religious text to support your position.
A great example is in the debate over gun control laws. Without espousing one side or the other, I can fairly safely and definitively say the US Constitution does support citizens' rights to own guns. For many a Libertarian, the discussion ends there. This is not something only Libertarians are guilty of. The other side of the debate often resorts to arguing context and semantics in an attempt to make the Constitution support their side. This clearly is just a case of people trying to win the argument rather than discuss and discover the best solution.
Similarly in the topic of marriage equality, a lot of the discussion has been focused on whether or not the US supreme court ruling was, in fact, constitutional. Extending that further, the topic goes on to "does the Constitution give the federal government the right to demand that the fifty states all allow same-sex marriage?" To me, this is not the true question that needs answering. Or at least, the answer to that question does not determine a certain action or inaction on the part of the federal government. (E.g., if it was decided that it was unconstitutional, that STILL DOESN'T NECESSARILY mean that the federal government shouldn't do it. I know, shocking.)
The Constitution was written by a bunch of men over two hundred years ago. Fallible, albeit brilliant, men. It isn't perfect. (It's damn good, else the country wouldn't have survived this long.) But it is still just a heuristic for finding the best course of action in what resembles a reasonable amount of time (insert your favorite 'inefficiency of bureaucracy' joke here). But heuristics can be wrong. So perhaps we should more often consider the question of whether or not what the Constitution says is actually the right thing. Certainly, departures from the heuristic of the Constitution should be taken with extreme caution and consideration. But we cannot discard the idea and simply argue based on the Constitution.
At the heart of the marriage equality and the supreme court ruling debate are the ideas of freedom, equality, and states' rights. All three of those are heuristics I use that usually point to what I think are best. I usually support states' rights, and consider departure from that as negative expected utility. However, there are many times when that consideration is completely blown away by other considerations.
The best example I can think of off the top of my head is slavery. Before the Emancipation Proclamation some states ruled slavery illegal, some legal. The question that tore our nation apart was whether or not the federal government had the right to impose abolition of slavery on all the states. I usually side with states' rights. But slavery is such an abominable practice that in that case I would have considered the constitutional rights of the federal government a non-issue when weighed against the continuation of slavery in the US for a single more day. If the Constitution had specifically supported the legality of slavery, then that would have shown it was time to burn it and try again.
Any federal proclamation infringes on states' rights, something I usually side with. And as more and more states were legalizing same-sex marriage it seemed that the states were deciding by themselves to promote marriage equality. The supreme court decision certainly speeds things up, but is it worth the infringement of state rights? To me that is the important question. Not whether or not it is Constitutional, but whether or not it is right. I am not answering that question here, just attempting to point out that the discussion of constitutionality may be the wrong question. And certainly an argument could be made for why states' rights should not be used as a heuristic at all.