That's a fair point, but now you can develop in VS on Windows and target pretty much every platform out there. They've also announced official support for Cordova, and they have the whole Xamarin thing going on. VS already has Python support, and Node.js tools are also being added.
This is starting to look like a pretty decent environment to work in.
But capability is half of the story. Tooling/ecosystems is the other half (re: MonoDevelop is still not up to the snuff).