Emulation doesn't help the platform that gains the emulated applications it just kills off any incentive for developing for the platform in the first place and the quality of applications goes down over time. The applications are, of course, also non-native and that brings with it the inability to take advantage of unique features of the platform. In the case of Windows 8 where it is trying to catch up to an older established platform (android) by adding value this is entirely counterproductive.