Firmware can handle it, yes, but not always in the most efficient way.
So this will improve things for people with fanless systems, but for everyone else it will just harm performance by throttling the CPU too much...
I also think that if we do want it in Workstation (I'm not sure we do) we probably want some notification UI for it to let the user know why their computer is suddenly extremely slow, like on OSX on the new macbook (you know, the one with only one port).