My guess is that it's also at least partially reflective of how .NET's status at Microsoft has changed over the past two decades.
Remember 20 years ago, when .NET wasn't just a managed software development platform? It was a company-wide strategy[1] that was meant to encompass more-or-less their entire product line. The whole Microsoft future was .NET, and they were going to have a .NET edition of Windows, SQL Server, Exchange, etc.
Since then, those plans have been dropped, Microsoft's (.NET-based) preferred GUI toolkits, WinForms and WPF, were replaced by one that is .NET-compatible but not .NET-native, etc. etc. .NET just isn't as central to Microsoft's identity as it was 20 years ago.
Which, I'm guessing, means that the .NET team is now a lot freer to go cross-platform without inviting the wrath of the Windows team.
I think the initial ".net strategy" was just a (failed) marketing exercise. It was supposedly some kind of grand vision where the .net framework were just one component and SOAP was another. They certainly did not plan to base Windows or SQL Server on the .net framework.
They did try a number of times to write kernels in C#-like languages. Singularity, Midori, etc.
This spawned a lot of interesting academic work that influenced languages such as Rust... trying to get high level features and safety without need for a runtime.
You're correct. I'm certain that you're fully aware of Midori, but as you alluded to, a Microsoft Research initiative, but never was on the official roadmap. .Net itself has been a great success. I was completely sold on .Net Core and .Net 5 is exactly where they needed to take it.
Remember 20 years ago, when .NET wasn't just a managed software development platform? It was a company-wide strategy[1] that was meant to encompass more-or-less their entire product line. The whole Microsoft future was .NET, and they were going to have a .NET edition of Windows, SQL Server, Exchange, etc.
Since then, those plans have been dropped, Microsoft's (.NET-based) preferred GUI toolkits, WinForms and WPF, were replaced by one that is .NET-compatible but not .NET-native, etc. etc. .NET just isn't as central to Microsoft's identity as it was 20 years ago.
Which, I'm guessing, means that the .NET team is now a lot freer to go cross-platform without inviting the wrath of the Windows team.
[1]: https://en.wikipedia.org/wiki/Microsoft_.NET_strategy