Let's ignore DirectCompute and look at just the 3D aspect. It's overrated. Remember when Crysis 1 came out and it was suppose to be the end-all-ba-all of graphics and it was marketing DirectX10? There was CVars tweak that allowed to have all the bells & whistles of DirectX10 in DirectX9 and people did this because it's less resource intensive and it allowed them to play Crysis at max settings on Windows XP.
What does Direct3D11 have to offer? Tessellation, but it is it really needed? In older APIs, we cause an alternative called "normal mapping". I've seen Crysis 2 DX11 vs. DX9 shots and I was un-impressed and that could of been done with normal maps. Hell, you need a Titan just to run the Witcher 2 with max Ubersampleing and it's only DirectX9.
In Defense of D3D11, I think tessellation makes stuff easier to add more model detail close up than to write your own code for fading in and out normal maps at a distance. I don't see a huge leap from a API last updated in 2003 Vs D3D11 as far as visual fidelity or I could be wrong, there could be a huge leap, but I'm not seeing it.
With each new graphics API comes new functionality. It makes it easier for the developers. The DirectX version doesn't necessarily play a big role in graphics fidelity, it all depends on how the developer uses the API and how good their lighting, models, shading, and textures are. Some Dx11 games may look worse than a Dx9 game. But then the majority of Dx11 games look better than Dx10 and Dx9 games. Metro 2033 looks stunning on highest settings.
There are some games that really make the different versions of DirectX sing, and some that don't. For good examples of DirectX11, I'd say look at the atmospheric effects in the new Tomb Raider game, Farcry 3, Metro 2033 and maybe Deus Ex.
I highly doubt at this point anyone would actively push the use of one version over the other for no reason. Like, I don't think the developers of Dirt 3 have any reason to make the DirectX9 water and weather so crappy if they had a choice.