I think the zen mania of one thing at a time has taken over the windows team and they're trying to minimize the clutter that people make on their screens. Probably it will actually help in focusing on relevant things but yes context switching sucks in 8.

I think Agile is more of a "getting things done" sort of a methodology. It doesn't care what you're developing or how stable the thing will be. It just forces you to create and manage something which can't be created through a static set of rules. For e.g. you don't need Agile to assemble a car, it's all taken care of by machines. But you can apply Agile to the unprectictable areas, be it S/w, management, research etc.