I think this is more of a personal maturation event than a result of any music that's being played on a given year. I felt the same way in 1993, and there's no way it was because '92-93 was worse than what came before that.I remember '98-'99 really being the first time I felt compelled to look beyond modern rock radio to find music that spoke to me.
Radio is a distillation process, by which the easiest consumables rise to the top. If you love music, you eventually hit a point where it's just not going to give you what you want, because it's never really all that great.