Under Satya Nadella, microsoft looks like taking a new breath, they have made Windows for mobile free-of-charge, really a small step since, well, few people care about Windows mobile. Both OS X and Linux are free-of-charge, let's not even talk about free-of-speech. But, hey, they have open sourced .net implementation... that's a big step. I really don't know under which terms it's open now, since we're talking about M$, one should take care. Anyway, it looks like an improvement.
So, under this new vision, what M$ shoud do next?
Currently, their free-of-charge IDE Version, Visual Studio Express, is limited by usage of plugins. IMO, this is really a VERY dumb model, creativity comes from the community. At last, it's very willing to come from it, but anyway, M$ prefers to make IDE plugins available only to paid customers of Visual Studio, which is sad since FOSS plugin initiatives can only honestly help paid onwers. This model is only "smart" in the sense of using express editions to lure users so they aftwards become addicts to buy a paid version. This must be fixed, express editions should allow plugins.
Kernel development in Windows is WEIRD. Right now it means you must have a paid version of Visual Studio to have the environment for developing drivers. Not only that, since now drivers must be signed to be used, a kernel developer must seek how to buy a certificate to sign its binaries, so anyone can load them. This comes through a third party signing authority service, which you must pay for. Can this be more unfriendly?... Please solve this.
Stop trying to bury OpenGL please, stop giving dubious excuses for not supporting WebGL. DirectX may be well adopted, but now, it seems like it'll never reach the status of OpenGL across desktop, mobile and consoles. As of now, it seems at last WebGL is being accepted in IE11, anyway... throughout the years I've heard OpenGL support would be dropped in Vista, not adopted in browsers, etc. OpenGL can't be buried now, since you're not the single player anymore, so, embrace it.
Stop with the license "small letters", where it's uncovered that, in the end, you're always seeking to take advantage over others, see this recent instance for example.
I won't come back to Windows any time soon, since it doesn't provides multiple desktops, a worth command line, nor a worth package manager, anyway, as I have used Windows before, and may still use it some time, having those things figured out would be helpful.
Feel free to add more redemptions points in comments!