California constitutional amendments are not really constitutional amendments in traditional sense, just a way to pass legislation by popular referendum. In theory requiring supermajority for referenda would be a source of a massive status quo bias, what would be extremely undemocratic.
California has a system for passing legislation by popular referendum. At least in the case of Prop 8, the use of the amendment process instead was to bypass challenges to the legislation's constitutionality. If we required a supermajority for amendments, but not ordinary referendums, it could stop the abuse of the amendment process to pass what should be ordinary legislation, subject to constitutional limitations.
I may be mistaken, but making it a constitutional amendment also makes it much, much harder for the legislature to alter it. If there's a thing called a "constitution," especially in the US, it's generally both different and superior to mere legislation. The point of constitutions is to ensure status quo bias; there's something undesirable about changing fundamental parts of your government when public opinion shifts by a few percentage points, as is likely to be the case with an amendment to repeal prop 8 in the next few years.
I have hypothesis that utility maximization is always a second order process - there's always some underlying selection process with its fitness, and only because it promotes traits that make agents agents act in a way that best approximates utility maximizing, adaptation executers seem to us like utility maximizers.
Now let's apply this to political systems:
There are also some hints how to design better representative democracy:
I used to think that direct democracy would be a major improvement relative to what we have now, but this analysis suggests that representative democracy (with small bits of direct democracy thrown in) should work much better.