What kind of apps do you need other than the media capabilities the console has and the apps already available on XBL?
Serious question, because I honestly don't see the need for apps on a Windows store for a device to play media. It's not a PC/tablet/laptop/phone. It sits in your media centre and plays movies/tv.
If everyone had that mindset then the app store boom would of never of started to begin with.
Using the store would mean anyone can deploy their software to that platform. Something I'm very interested in.