>the open source ecosystem essentially does not exist at all in the .NET world
I've been complaining about this for years as a fan of both C# and OSS and now more recently as an employee at Microsoft. It's a problem all across the .NET technology stack. EF gets huge attention everytime they have a new release and add a feature that NHibernate has had for years. If I can't find help on StackOverflow and it's not the 1% of MSDN articles that aren't useless, there's no where to go ask for help. There aren't forums, I've yet to find a reliable IRC room, etc.
It's too bad too, I really kind of like the JS WinRT development model and with some open source grooming could have a lot of neat utilities and kits and layouts built for it. There is huge potential for benefit from a Bootstrap project for Windows 8 apps, but I don't know who would take the time to make it friendly and packaged given the amount that .NET developers seem to love to work in isolation and reinvent the wheel.
edit: Also, the forums are just a joke anyway. Try to post something with some code, or an error, or a log or just something with multiple lines and watch as it's rendered as one huge chunk of text because they're stubborn and force the usage of their tired, unusable RTE.
I'm with you, I'm sitting here thinking that third party developers are the most important thing for Windows platforms right now and they're arguably the weakest. I've seen many complaints (still) about onboarding. They've fractured an ALREADY fractured community of developers further by introducing another runtime that is incompatible (the shim library that ONLY works in C# doesn't count) with .NET and a third MS variant of C++. The examples for WinRT apps are severely lacking, there is broken navigation between them and/or the examples are too trivial to compose into an actual, even just example, application.
(edit: I should clarify. A lot of my frustration in this regard is not with Microsoft, but with the community of Microsoft developers who seem unkeen on using anything but the official Microsoft stack regardless of alternatives. And who seem unkeen on fostering a community the way other OSS projects do. I've received more non-.NET help in a single IRC room in a few hours than I feel like I've ever received from any .NET resource EVER (including a team of MS experts and alumni that were at my disposal for two years).)