I got bored with Diablo 2, way too much grinding for me to handle - it was when I was in that jungle place, fighting these endless droves of worms and bugs and other revolting infuriating things, that I realized how much time I was burning doing this tedium, so I said screw it. At least JRPG's give you a bit more sense of story progression (Diablo 2 had a pretty cool story both from what I experienced and watching my friends play, it's just the cutscenes and other story advancers were too few and far between IMO)
Haven't really played too many other classic or JRPG's, just modern hybrids with other genres like Mass Effect and Deus Ex, and I'm playing FFX right now for the first time, so I'm still pretty new to the genre!