This does exist, we call it Java (or C# or probably a dozen other implementations)

The big tradeoff you're making is that you have significantly less time to run your optimizer, since not everybody has a beefy machine or the patience to wait a day for their browser to start first time.

You could try doing optimization ahead of time, but I think (I could be wrong here) you would inevitably end up adding in some CPU assumptions if you went much further. This also somewhat conflicts with an advantage of VM based execution, that new optimizations apply to old binaries.

I'll also note that hand rolled assembly/SIMD code still beats compilers at the extreme end and you would either have to throw that away, or get all the disadvantages mentioned above without all the advantages