LMAO, I think this post is so Funny, Why you ask ?. Well, they are only just releasing games with DX10, never mind DX11. In my opinion DX10 has been a complete failure. Look how long DX10 has been around. We will have to wait another 18 months before its main stream, and by then ATI and nvidia will of released another 2 cards each.
THe only issue is, you're COMPLETELY wrong, dx10 was cut back in spec just before release. Meaning much of the dx10 functionality was removed, almost all the improvements were gone and most importantly, for those game makers 1-3 years into making DX10 games, half the optimisations and improvements simply didn't work anymore.
The few games that came out with the original DX10 spec, which is basically DX10.1, ran some 15-20% faster under dx10.1 than dx10.
So had Nvidia had hardware, and DX10 spec was never scaled back, most games were designed to use it, gain a significant advantage and were ready to go.
Once the spec was dead and half of the stuff writen for DX10 literally couldn't work, DX10 was dead, its unsurprising companies didn't put a lot of effort into, adding extra particles without any extra optimisation. One of the few things left in meant particles had a lower overhead, so you could use a lot more, however more particles drawn = more processing to be done, this is fine when you gain a nice healthy speed boost, but with the speed boost parts of DX10 not there anymore, the particles were unusable, or in the few games that used them excessively, killed performance.
DX10 only failed because Nvidia screwed it, they made it a pointless thing, DX10 spec couldn't change and so the whole industry was stuck till dx11 came about.
DX11 ISN'T a minor upgrade, it will offer very real and tangible benefits, and because a bunch of the improvements in DX11, are there in DX10.1 also, which developers had originally started building games to 3 or more years ago, you'll see a VERy fast uptake to DX11, because coders are experienced in it, because DX10.1 has been around for ages and already makes a very decent difference and because there is a pretty major speed improvement in DX11, meaning theres a tangible reason for DEV's to put the effort in. Once DX10 was neutered, we were simply at the point it offered nothing at all over dx9, except extra cost an expense in more coding, more debugging and more support issues. Now there is a clear benefit to the extra effort, not to mention Windows 7 pre-orders are huge, people like it and most people will indeed go to Windows 7, so most people can use it aswell.
Its pretty simple, imagine you're a coder, someone comes up and says, rewrite this game to use DX10, but theres no reason to do so, its just hours and hours of work, for dozens of people, over months, for literally no benefit.
Then go up to them, tell them to use DX10, but tell them it will run 25-40% faster, so they've got far more power to play with, so as coders they can add more complexity and detail to scenes, they can really push the game further and do more things on the same hardware, they'll do the work, because theres a benefit.