I say only add more if there have a logical meaning distinct from agreement, not just more gradations. To me, Like is a conflation of “This was worth reading” and “I agree with the sentiment” which are two very different things. I think two options “recommended read” and “I agree” would be the two meaningful categories that one could still quickly decide to click. I think the BB crowd has expressed this reaction to posts on many occasions “well written, well argued, but I disagree with your conclusion.” If there were ever to be some kind of visual indication of which comments are popular, such as their being highlighted, or floating to the top, it would have to be based on readability, not popularity, in order to be truly interesting or additive in a climate like BB.
I do think that “don’t make me think” can be fairly applied, even in a system of thoughtful people making thoughtful comments. Liking is very different from posting and reply, in both form and function. It serves a commenting system to make liking simple, as the likes are just dressing on the comments,