I believe in one of the Trek convention clips, Wil Wheaton gets into this. He said that one of the biggest longings that people have over the TNG, DS9, and VOY series is how utopian everything is. There really didn't seem to be any real conflict to come into play, at least until the Borg enter. After that, some of the utopian thinking went out the door, as conflict started to come back into the timeline. Think about it.. take a TNG episode, like Angel One, and pit it up against parts 1 and 2 of Reunification. Then pair all of that up against later episodes of DS9 when the Jem Hadar and the Founders come in. People, at least according to Wheaton, missed that conflict, and that was also really prevalent during TOS.. They took out a lot of the social commentary and put back in the "cowboy diplomacy", and things started to go a bit downhill from there.
BL.