I think that’s a bit of perspective. One reason “the grind” is so reviled in Everquest is that most people really want to get to the endgame, which consists of marching through a progression of boss mob encounters which are generally reasonably varied and (for me at least) quite satisfying to accomplish. Yes, eventually there’s another expansion and more boss mobs to fight, but I don’t see this as any different than adding on Throne of Amn or whatever to Balder’s Gate II, or, for that matter, Balder’s Gate II to Balder’s Gate I.
The difficulty is more that to “finish” BG you just need yourself. To “finish” any EQ expansion, you need yourself and 45 of your closest friends and, well, that takes a lot more time to organize and get through.
The whole appeal of these things, though, is supposed to be their ongoing nature. Why someone who actively needs some type of “ending” would get into one in the first place is a bit puzzling to me.