My idea is actually that MS did not really try.
That's absolutely insane. Both to have actually been in that position and to think that. You'd better believe that MS tried. They were however tempered by reality and some amount of self-awareness, unlike some of the competition. And you'd better believe they're trying now in mobile too.
The world of computing is shifting fast. The mobile space, including tablets will soon account for more money than traditional PC-based channels. MS is SCREWED if they get left behind. It's what I said before, they may end up as strictly an applications company.
BTW, if MS don't start cutting back on the other Windows licenses, I think Nokia is going to be no better off in the long run than they would have been otherwise. They will not likely dominate like they did back when no one else was actually making smart phones.
The Nokia-MS relationship had better produce some very special products, not just some random run of the mill Windows phone anyone else could have deployed.