That would necessitate a major overhaul of the kernel(?) & the OS scheduler, didn't we see how inefficient Windows is thanks to bouncing threaded workloads from core to core?Because of context switching.
So in the Blender example mentioned earlier: heavy rendering would be run on the "big" cores, while light background stuff (OS, networking etc) could be kept on the small ones. That means less switching and less performance lost.
What you're suggesting is not possible on Windows now, though I also believe this is the most interesting chip from Intel in a long, really long time!