I agree! It'd be especially useful when restarting after updates, etc. I have a bad habit of stepping away to do something else while it restarts, then coming back to find it in the wrong OS.
The weird thing is that I'm pretty sure at one point I had a bootloader that behaved this way, though it's been long ago enough that I can't remember if it was a version of Chameleon or Chimera or something completely different.