The change in architecture has nothing to do with greed. The change is done to make it much more easier for developers. It is also understandable why they wont include PS3 hardware in the PS4, because that would increase the price of the PS4 (the inclusion of both the PS2's CPU and GPU in the first PS3s was one factor to why Sony lost money on each sold PS3).
It has also not been specifically mentioned that digitally downloaded PS1 games wont be supported on PS4. PS1 emulation is done 100% through software, so that shouldnt be much of a problem. It depends a lot how much time and money it will cost to make a PS1 emulator for the PS4.
It is rumored that the Xbox 720 will also change architecture by the way, so i wouldnt expect backward compability there either. But we'll see =)
EDIT: Or maybe you're only referring to the PS1 stuff about transfering stuff over from the PS Store from PS3 to PS4? I wasnt sure since you later on said that the PS4 looked like corporate greed, but the PS4 is a lot more than just playing old PS1 games of course.