But there again, games developers aren't going to care about an cool new IE feature either unless they're building games that run exclusively or primarily on IE

But there again, games developers aren't going to care about an cool new IE feature either unless they're building games that run exclusively or primarily on IE, which I suspect is a very small market. It's not that "nobody runs Windows", it's that "relatively few people who would find snazzy new IE features useful" run Windows.