Does Microsoft really care?
I mean, they are primarily and always have been a software company. They don't make PC's they just sell a bucket load of software and make a bucket load of money in doing it, and by a mile are the most successful in the world at doing so.
Sure they make a few mice and keyboards, and have played with a MP3 player and have a nice gaming console out which is pretty much a world leader.
Are they going to fret about not have a own build tablet?
They can just write OS's and Apps for all other tablets and make a mint without having to worry about hardware.
You bet they care. It would be nice if MS could just do their own thing, and excel at it, but in the corporate world, if they don't continue to expand as fast or nearly as fast as their competition, eventually they will be in danger of a take-over. Not saying this is going to happen tomorrow, or even any time soon, but Microsoft absolutely cares about where the computing world as a whole is going.