(on that note, I'm constantly annoyed that despite it being Nvidia specific, everyone supports CUDA for everything cool).
I understand companies have to do this to segregate their products and that it's impractical to have separate fab lines for a chip family for this kind of difference. It's still something I think AMD has a competitive advantage on though and they really need to push that alone (unless they just don't really want to - to sell their own high-end professional cards).
A worse example of this is Nvidia cards not running in systems that have AMD graphics cards in them. Which means, for example, you can't buy a low/mid-range Nvidia card to sit in your system as a dedicated PhysX/CUDA card. I'd consider such a setup for my system and I imagine there's probably others like me out there.