Actually the best example is OS/400 mainframe system from IBM.

The kernel is a mixture of Assembly, C++ and Modula-2, with a JIT.

All user space code compiles to bytecode.

The kernel JIT compiles the applications on first execution. Afterwards the application is validated against generated native code, and re-JITed again if the bytecode has changed between executions.

So Microsoft's attempt was actually nothing new.

I would say, no, not at all. Rewriting your entire userland is not similar to adding a script interpreter to be used for writing kernel extensions.