Oubliette. I share some of your frustration with the like and dislike buttons. I feel that there was more and more personal discussion before the buttons. I really would like to know what it is about my comment that you dislike because sometimes the posts we make have multiple points in them.
Also, it's nice to get a personal response for a liked post for a similar reason, as well as also better relationship building.
However, I think part of the issue is that forums are asynchronous types of communication. If you are reading comments that are several pages long and began several days ago, hitting like or dislike on a comment in the middle of an old thread might be the most appropriate form of feedback.