I'd say .NET is surprisingly immature considering it's age and it's popularity, at least compared to JVM and JS options.
Don't get me wrong I think .NET is great, and they've made some smart decisions that allow it to be competitive with much less engineering work on the VM.
As well as not having escape analysis it also lacks tiered compilation which is a much more pressing problem from my perspective, and is being actively tackled now.
Looking from the outside, but also following everything that comes out of MS and MSR, I think it was a political consequence.
There was always the DevTools vs WinDev differences regarding the role of .NET in Windows, and for a while it seemed Microsoft has happy having .NET just be good enough.
Thankfully they have changed their mindset and are improving .NET to be as close to C++ as possible, at least for 99% of the use cases where using a GC language is an acceptable trade off.
Don't get me wrong I think .NET is great, and they've made some smart decisions that allow it to be competitive with much less engineering work on the VM.
As well as not having escape analysis it also lacks tiered compilation which is a much more pressing problem from my perspective, and is being actively tackled now.