How do I upvote myself again?

I'm going to guess the answer is yes, but possibly not out of the box.

I don't know about emacs, but MacVim does.

What value would they have if they did?

The key bindings and their customizability, standard or not, are part of the reason these tools are better than the HID-blessed equivalents.

This question is like whining about a F1 racer because it doesn't have windshield wipers.