I don't even understand this "everything must be a super simple little app" approach that both Apple and (and now because they're a big copy cat) Microsoft are taking. Is this really what the populace wants? I understand that constraints often yield the best designs, but this is a little crazy.
And as far as the dev tooling - that was one area that Microsoft was notably competent. I really can't see how this will benefit them in the long term. Seriously, what is the upside for them? A few more Metro apps? They'll win the battle but lose the war.