The vast majority of people upgrade OS when they buy a new computer. This means the adoption rate of a new OS is largely determined by the rate these people buy new computers.
The big PC suppliers like Dell operate on razor thin margins so in order to make money they need high sales volumes. If people where not buying computers because of vista there would be a big problem. Dell and co would have to get people buying somehow, raise prices or lose lots of money.
Dx11 is going to suffer from this exact same problem. It's just being released later so more people will have replaced their ageing xp computers with new machines. The problem is still going to be their. The percentage of users with winxp is just going to be smaller.
http://store.steampowered.com/hwsurvey
The steam stats show 55% of users have winxp. What would it be if vista had a really good reception? 45%? 35%? 25%? Still high enough to be causing problems. Nobody excludes 1 in 4 of their potential customers without very good reason.
MS haven't shot themselves in the foot, they shot everybody else in the foot. Microsoft have very little competition. What are game devs going to do? Start writing for mac or linux?
I guess dbpro is a good example. Why would TGC invest money porting dbpro to DX10 when so much of the potential market would be unable to use it?
By way of demonstration, he emitted a batlike squeak that was indeed bothersome.
