Intellij is amazing. Note that jetbrains built resharper to de-suckify Visual Studio. And many of the refactorings that we all take for granted were invented by Jetbrains.
No one is stopping 'in theory', but may be because there's no IDE close enough to Visual Studio for making something close enough to Visual Studio stopping people? ;)
Tried to buy a Visual Studio license for porting our game to Windows Phone last year.
Ended up paying $2K for a version that was able to build WP apps, but not allowed to release them.
VS + VA used to be fantastic, today it's just a piece of ... overpriced crap.
But maybe expecting more from $2K+ software (VS) than from FREE software (xcode) is wrong.
Not sure what you are talking about. Visual Studio Express allows Windows phone development for free. Of course, for releasing they charge money (much lesser than what Apple charges).