A lot to agree with JM in your post.
From what i understand you can switch between ,metro and the standard desktop - in w8. Its puzzling to me that all the music apps I have seen for touchscreen so far, without exception have been 'toys' rather than real apps, perhaps we await win 8. I can think of lots of ways that touch could be utilised, for example faders could be on screen in touch and you could fade without using a mouse.
I am not entirely convinced that this is the way to go myself, but it seems everything is going this way, from megapowerful phones to the Ipad and clones.
I could see the phone being used as a hand held interface for a large screen in a pro studio. So, for example the phone app could have a fader or two on it and clicking and dragging it would, via blue tooth, effect the larger DAWs sequencer. There also must be new innovative uses for touch, for example maybe you could strum a guitar, or a harp. Synths like omnisphere are sure to make use of it, in fact omnidsphere has start to do so.
Although at present many of the OS's dont really support Audio sequencers, I can foresee someone developing a must have app that gives a decent audio engine and compatibility, rather similar to ASIO. Maybe even a particular tablet coming out with the right hardware for musicians...

I hope the whole audio engine gets revised. And as the buttons marked strings that play trombones.... inexcusable to any other programmer and so simple to fix.

Win 11 64, Asus Rog Strix z390 mobo, 64 gig RAM, 8700k