If they cared to see their app ecosystem grow, they wouldn't charge developers 100$ (which is actually 1$ more than this greedy evil empire of Apple does :)) for a licence you need even to install your app on your own darn phone
This uninviting attitude of theirs was one of the reasons why I ultimately became an Android dev (once I decided to move into mobile apps), even though I had C# / WPF background so picking up Windows Phone would be the most natural next step... And Java admittedly sucks in compare to C#
Unless you are developing for iOS you can't have all of the devices your users might have, being able to solve issues remotely is huge. Especially when you are dealing with hardware issues on all of the Windows hardware out there.