Well - and I must stress I can take 'em or leave 'em - they wrote some great anthems that the kids latched onto. And lots of those kids also picked up guitars because of them... I'm sure we'd all agree that's a good thing.
I wouldn't say the musical scene was dire at the time, but it was in danger of disappearing up its own derrière. Oasis reminded us that normal people can start a band, have fun, and make a shedload of money.