I think that you are basing all of this on an assumption that Microsoft is shooting from the hip and their long term plans are not carefully thought-out. ...
I'd argue that nothing Microsoft has done in mobile has been well thought-out. Just off the top of my head:
1. The futility of trying to convince the world, for 10 years, to buy Microsoft Tablet PCs.
2. Killing off Windows Mobile 6.5 with absolutely no app or data migration path to Windows Phone 7.
3. The failure of Zune.
4. The failure of KIN.
5. Choosing one manufacturer (Nokia) as their prime hardware partner at the expense of all other Windows Phone device makers.
6. The non-upgradability of 1-year-old Nokia Windows Phone 7 handsets to Windows Phone 8.
7. The inability to decide between ARM or Intel for Surface.
8. The inability to port Office to a mobile OS without a "desktop."
The only thing that Microsoft is carefully doing is anchoring themselves, permanently, to legacy desktops and laptops. Anchoring themselves to their past. Their Windows glory days. The '90s.
... That said, I don't quite understand the reason for the Gaming Tablet either, but in my recent experience, I find it hard to believe that it is not a carefully thought out piece of the yet to be seen bigger picture. ...
I find it hard to believe that the Gaming Tablet is not simply another Microsoft knee-jerk reaction to competitors' successes in mobile. Ballmer is so used to crushing young, vulnerable competitors with FUD that he either 1) still thinks FUD works, or 2) simply doesn't know what else to do other than to spew FUD. Even now, against deeply entrenched, dominant, aggressive players like Apple.
A year from now, I'll be adding #9 to the above list:
9. The failure of the stillborn Gaming Tablet.
