Visibility is everything at MS. Is there a line item on your review for "W8 App d/l #s"? No absolutely not. Are there positive career effects for your boss being able to say "yeah, so-and-so wrote an early Win8 app and got a bunch of good reviews and X hundred thousand downloads and got it highlighted in MSDN as an early win for the platform"? You'd better believe it.

(ex-MSFT, 14y)