Theres still great music being made, even in the 'mainstream'.
The problem with the current trend of living is that it is a throw away culture, music is no exception, the music made by the general mass is for short lived fast profit generating, find a trend and bleed it dry. Dare to be different and that isn't deemed profitable.
Theres still plenty of good music around, it isn't main stream or popular for the most part but it is around. Miike snow is a perfect example i feel, great songs, really diverse album, music is featured on tv and media but isn't played massively on radio or publicized hugely (not adored by the general masses), Mumford and sons are great too, obviously only personal preference but examples that are noteworthy.
As for using Oasis to emphasize this i think its a little unfair, they birthed an era and to say music today lacks because people are not doing what Oasis did back then implies that bands that special were throwing hits in the charts left right and center!
Side note+++
To add, there was just as much PAP around then, babylon zoo's space man springs to mind instantly when i think of Oasis, funny that how an era can imprint itself so deeply, the two have nothing to do with each other than they were released in the same decade!