Has it? Or is this just some people on forums talking amongst themselves?
How would you suggest MS/SE quantify it then? Everything about Tomb Raider right now, from a community standpoint, has no monetary value attached to them because the game was so far off that any pre-order cancellations must have been minimal to none.
Official tumblr comments? Over 9000 comments on the original post, and over 200 on the new FAQ. A glance through of the comments are enough to tell that 95% of them are all negative comments. And the average of that tumblr? Less than 10 per post even on official news.
Crystal's Facebook feed is being spammed with nothing but terrible things being said about them and this deal. They've like quadrapled the amount of FB post comments they've gotten post-Gamescom, and none of it is positive.
TR forums have been cited before by other posters ( not really aware about TR-specific big forums to make a judgment call ), but citations of the response from those forums by other GAFers also put it as mostly negative.
GAF? Mostly negative. Twitter? Mostly negative, but I didn't keep up enough to see how wide-spread it was and over how long.
And the additional point to this is that the games media is painting this as a 'bad thing' instead of a 'win' for Microsoft. A lot of pieces/opinions from 'games journalist' are basically saying that as a timed exclusive, it's not 'that big of a deal', and instead we're seeing articles that frames the whole thing as 'not exactly a flattering thing' for Microsoft.
Maybe you're right and final sales of the product will be unaffected by all of the above. But right now, MS, SE and Crystal are not getting positive feedback at all. Even if it's a vocal minority, it's a very, very, very, very loud one.