Oasis were just a bunch of lads from manchester, a product of the madchester (for those in the USA maybe not in the know these were bands like Stone roses, Happy Mondays and even the Charlatans in their early days) scene and a passion for the beatles. They might have done some crap records recently but in the beginning they didnt care, noel didnt care if he used the same old chords or just the one blues scale, it was about the music and Definitley Maybe showed that. Oasis are more or less the reason I picked up the guitar, even though I wouldn't cite them as a major influence anymore, and I rekon the same would be said of every british guitarist who first started playing 12 or 13 years ago.
As for pearl jam, I firmly believe, (even though they were, in my opinion, from one of the greatest musical movements ever), are average. I can name a hand full of songs I'd like to listen to more than one, and all of them are on 10. I even saw them headline leeds festival, got right to the front, hoping they'd convert me. I never considered them to be that big at all, even in the wake of 10. From their generation theyre nothing but 3rd of 4th best (I'm certain Nirvana, the smashing pumpkins outsold them on a grand scale).If they didnt want to make it big then they shouldn't have written stadium rock. They won't stand the test of time, being 21 they sound VERY dated to me already.
Obviously, this is just an opinion, whoeve might agree or disagree.