One possible value of more diverse buttons would be more specific feedback to the comment author, as well as providing data to all participnats about what type of comments "do well" here.
As it stands, highly upvoted comments appear to me to mean the group agrees, strongly downvoted comments just disappear & comments with low votes are ??? (possible answers: ignored, too technical, wrong, redundant, obvious, disagreed with but not strongly, poorly written but so poorly written that no one wanted to make fun of that guy, late to the discussion so no one saw it because no one reads that thread anymore, some combination of the afformentioned, other group in-fighting and politicking I'm not privy to, etc.)
Of course the buttons would only be valuable to the extent readers will participate and use them. Is there an incentive to voting beyond the general good & welfare of the forum?
As the premise of the topic, I think so, yes. If relevant and definitive comments such as those described are being ignored, I think that poses a tangible problem. I've actually thought this for awhile, and I thank Kaj for having the guts to say-so. I'm not concerned with what kind of posts do well; I feel confident I could play the part if there were motivation for me to do so. What I am personally interested in is optimizing the ongoing discussion. The votes I receive on the comments I'm making here will let me know a deeper quality of information about ...
Every now and then, I write an LW comment on some topic and feel that the contents of my comment pretty much settles the issue decisively. Instead, the comment seems to get ignored entirely - it either gets very few votes or none, nobody responds to it, and the discussion generally continues as if it had never been posted.
Similarly, every now and then I see somebody else make a post or comment that they clearly feel is decisive, but which doesn't seem very interesting to me. Either it seems to be saying something obvious, or I don't get its connection to the topic at hand in the first place.
This seems like it would be about inferential distance: either the writer doesn't know the things that make the reader experience the comment as uninteresting, or the reader doesn't know the things that make the writer experience the comment as interesting. So there's inferential silence - a sufficiently long inferential distance that a claim doesn't provoke even objections, just uncomprehending or indifferent silence.
But "explain your reasoning in more detail" doesn't seem like it would help with the issue. For one, we often don't know beforehand when people don't share our assumptions. Also, some of the comments or posts that seem to encounter this kind of a fate are already relatively long. For example, Wei Dai wondered why MIRI-affiliated people don't often respond to his posts that raise criticisms, and I essentially replied that I found the content of his post relatively obvious so didn't have much to say.
Perhaps people could more often explicitly comment if they notice that something that a poster seems to consider a big thing doesn't seem very interesting or meaningful to them, and briefly explain why? Even a sentence or two might be helpful for the original poster.