at the risk of sounding like a brainless fool, it is, in my opinion, just bad for business if a game company released a console that uses discs, that cannot run games from one of their older systems that used discs.
Xbox in particular angers me with this (I WANNA PLAY FABLE: THE LOST CHAPTERS ON MY 360 DAMNIT!!)
PS3 has enough bad publicity right now, they might want to think about re-adding backwards compatability (not that it matters to me, as i have one of the original PS3's that can run PS2 games).
my two cents.