Is you most certainly do not need a mouse with your Surface RT which will only have 4 or so years of Support and your Win Phone 8.

8 is ideal for those platforms but I see it as next to useless on the Desktop. Or as my Father would say Windows 8 is as useful as Teats on a Bull.

I just don't see 8 being widely adopted on the Desktop as it currently stands but it's an ideal user interface for Mobile Devices.

Col