At a time when there are few reasons to buy a PS3, why remove a reason for buying one - backwards compatability, its just stupid. Sony themselves have said they will be removing the vital ps2 graphics chip from all models, and don't assume that total software emulation will ever happen, the ps2 is a complex design.
If no models have backwards compatability in the future as they say, then that will rule out a lot of people selling their PS2 consoles to fund a PS3 purchase.