The issue is, I still believe that MS absolutely needs to be in the mobile space for Windows to stay relevant the way it has been. They simply cannot afford to become enterprise and professional user only. Which means they need a mobile play and that's where I think changing the category is a mistake.
That's definitely the case, I'm pretty sure even MS can see it. Windows is being attacked from the peripheries and essentially has been contained to the PC. I presume this is why google made a big deal of not supporting WP. It's clear google has ambitions beyond the phone, and have targeted education with chrome books. This is a big deal and Dan touched on it in the last podcast with his (iirc) nephew. Once they get brought up in that ecosystem, it's what they know and what they will largely continue to use.
This is where windows dominance from enterprise was such a big deal. People were learning how to use windows computers from work, and no doubt, that's what they were buying for their own computers.
Smartphones are different, since user adoption didn't come from enterprise, it clearly became dominant purely from the consumer space, and I think in many respects, that has decided where enterprise went. In other words, enterprise went down the consumer path because of its sheer dominance. The downfall of blackberry is a great demonstration of that.
In those instances, MS has mostly been boxed in and left out of major growth areas. It appears that MS recognise this, and are doing things to correct it.