There is an entire thread of people complaining they wouldn't buy the game, even if it was fun as heck, because it didn't support DX11. I don't care what you guys want to label that behavior as (elitist, a sense of entitlement, whatever...), it is disgusting, and PC "gamers" like that can fall of the Earth as far as I'm concerned.
If a game is fun, and isn't screwing me over with some terribly restrictive DRM, and is a reasonable price I'll buy it. DX version should be almost inconsequential in a decision on whether or not to buy a game, unless the actual required DX version is higher than your card supports. Sure, it's nice when a game is gorgeous and using your hardware to its fullest, but if a game is fun, does it really matter one way or another?
Reminds me of the people that refuse to even try Minecraft (for FREE!) because of the graphics. How is it any different that people refuse to try Crysis because of DX version?
If I went to Burger King after I saw the new BK Stacker commercial, and I ordered one, I would expect some things. When I placed my order, I know that what I receive will be based on what I pay for, 1 patty with cheese and bacon for $1, 2 patties with cheese and bacon for $2, and 3 patties with cheese and bacon for $3. I know this, because this is what I was told I would be getting based on the advertisements and pictures.
However, Crytek did something very interesting. nVidia offered them money for advertising using their game, and on nVidia's flagship cards, they advertised the power of DX11 in games such as Crysis 2. Interesting. This was also, if I recall correctly, advertised on their website, as well as in interviews with the team. All of this was being said during the pre-ordering stage of the game.
Let's go back to my analogy before, with Burger King. If I got up to the first window, typically where you pay but do not receive food, and I am told that I will NOT be getting 3 patties for my $3, but instead, I would only be getting 1, and I could return later that day for my 2 other patties, I would be freakin' pissed.
If I pay for a game, and certain features, based on the reputation of the company preceding my purchase, I have expectations. Crytek failed those expectations. Terribly. That is what people are pissed about.