Okay, I officially Don't Get all the hating.
I saw this coming with the very first Guitar Hero, as well as genre versions, Blues and C&W, frex.
Sure, Aerosmith may not be your bag of tea, but the reason they were chosen is that they have a long enough career, with a correspondingly large body of material from which to pull an appropriate progression of songs, they have a large enough audience base to guarantee sales, which a heavier, more metallic act might not be able to provide, and they're not so big as to be too expensive, as Kiss would probably prove to be.
They're just right for test marketing a single band edition of GH. Not my bag of tea, either, though. I'm holding out for Tap.
As far as complaints that it's only more of the same...well, yes. If there's one thing people want from music games, it's the music they like. There really isn't anything to add to the core gameplay of GH(*), and in point of fact, GH is only slightly different from Frequency and Amplitude, Harmonix' first two PS2 games. The assertion is that GH and GH2 are only good with the original songs they came with, and new playlists need not apply, and I call BS.
*: There is at least one innovation waiting in the wings, but neither Harmonix nor Activision are the companies to bring it...now that we have a mechanic and controller for guitar play, that mechanic now needs to be integrated into a narrative game, maybe, say, Crossroads frex, or Tenacious D: the Pick of Destiny, or Six String Samurai, or something wholly original. Maybe the makers of Patapon would make a PS2 game that takes advantage of the guitar controller...