80% of the acts are musical geezers (sorry eminem). I think people don't appreciate the amount of music available to kids these days. They have everything available to them. Gone are the days of being stuck listening to your brother's Kansas or Boston album. Songs are released individually, they don't have to listen to an entire album. Sure, they miss out on deep tracks on albums (Mr. Brownstone), and will never appreciate the joke of Trent Reznor putting 99 3 sec silent clips before getting to a bonus song, but they have a lot of great current music available to them. You can argue whether the experience is better or not, but it is definitely more efficient, and gives the kids plenty of current music to keep them occupied. That also makes them less likely to hear older music. As far as these acts being old, they are, and the kids recognize them as such, if they even recognize them.
For the record, I don't find this anything new. I remember the spring of 2001 talking to a young lady and being told Pearl Jam, Nirvana, and the Butthole Surfers were the classics.