Today, I can't see any justification for not at least running a dual-boot of Windows to run the games you want when they ship--as opposed to having to wait months/years, and many times never seeing a port made of the games you want. Today, there's no difference in the hardware at all, and if you're someone who loves computer gaming it doesn't make any sense *not* to run Windows.
There are many reasons not to run Windows. From privacy and security concerns to dislike to Microsoft's practices. The bottom line, people use other operating systems like Linux for a reason. And Linux gaming is improving, so for a growing number of people there is no reason to use Windows at all anymore.