from my experience with raiding in old WoW and even EQ1 some players loved that only a small percent got to see or beat the raid content. it made them feel superior and more special than other players. some folks didn't act that way, but in others it created a very hostile attitude toward those who couldn't raid or didn't want to. you can still see that kind of hostility today with heroic/normal raiders lashing out at Blizzard and other players who can't or won't raid normal/heroic.
lfr and flex raiding is a great idea. it's not evil. just because someone else gets to experience the content doesn't make a normal/heroic raider's experience less valuable.