Microsoft needs to make sure developers have access to all the same stuff they already have when making desktop apps when it comes to MIDI and audio in Win8 Store apps (which they currently don't).
http://www.sonicstate.com/news/2012/11/01/why-microsoft-needs-musicians/

By the way, Pete Brown did a video with Jordan Rudess a while ago showing off his Win8 app


Professional musicians and other creative types using your stuff is great free advertising.