Personally I loved the idea of a support class, but in practice this did not always seem to work out as well as hoped. What I would have loved to have seen, in a 40-man raid, was raid-wide UNIQUE buffs for playing support roles. As an example, if a feral druid in cat form provided a raid-wide 5% buff, and that buff could not come from any other source, then that class would be considered mandatory. I would have loved to have seen situations like this crop up, if the idea of the 40-man raid had been taken to its next logical level.
I'd actually still like to see this situation happen in Classic wow, but I do not know if they will have the "vision" to do stuff like that... your passive contribution to the raid would be absolutely justified regardless of your individual numbers. That is the sort of thing that I wished Classic wow had done, because it would be nice if there were a few roles i the raid that people could play without needing to be outstanding twitch-gamers in order to contribute.
Today's mythical wow raids are more about individual excellence, and less about teamwork. It's one thing that I liked about Vanilla wow, was that you could have people who underperformed on an individual basis, but you could still justify their raid spot with tertiary, passive contributions. Those days are kind of gone, and I thought they would never come back... but now I kind of have hope that maybe they will...