One has to keep in mind when Jaco played. Primarily, it was the 70s up to the mid 80s or so. In the 70s, very few bass players were doing what he did the way he did it (fretless, staccato lines, lots of mwah and midrange honk, etc.). The fact that he could play solos that sounded a lot like what a horn player would do but on bass is what made him a unique player. If you think what he did was easy, try playing Teen Town on a fretless and in tune. If you not primarily a fretless player (I'm not) you'll find, I think, that it isn't easy and requires a lot of practice and skill.
I don't get most of the new generation (Fieldy, Mark Hoppus, Pete Wentz, you name them). To me, slapping, popping, tapping are a lot of wankery if not impressive (for the record, I'm not a master of any of those techniques, but I'm trying, and I can certainly respect and admire those who have mastered them - anyone want to give me lessons?). Yet, everytime I go into a GC, every young player I hear is doing just that. Most of them can't play a major scale when asked, however. To each his/her own, I guess.
I guess what really confuses me these days (for the record, I'm 45) is the amount of importance placed on image over substance. Sure, image is a big part of any performer's draw; Elvis wore gold suits for example. But I should think there would be some chops to back it up. Jimmy Page wore huge bell bottoms with dragons embroidered on them in "The Song Remains The Same" movie, but he could play. Bootsy Collins wore some really interesting stuff, but he could really get funky. Pete Wentz? Other than combing his hair over his face, I don't hear much that inspires musical confidence. And that guy has a signature bass.
For me, Jaco is and remains a primary influence. It's interesting that over 20 years after his death, people are still talking about him, love him or hate him. My guess is that 20 years from now no one will know who Pete Wentz was, or care, but that, of course, is my opinion. We all have them and we all know that they, uhh, don't smell too good.
My two cents,
Alan