Word processors use up/down keys to move up/down one line, at the same index, or the beginning or the end of the previous ‘ next line, if they exist. It can work.

Acme is opinionated and it’s a good thing if it fits its userbase. I am actually quite fond of many design decisions and maintain patches to workaround defaults that could drive me insane.

My personal feeling is negative on this matter, just as if I would need to reach to the mouse to delete a character. Up and down mapped to something like page up / page down feels as infuriating as those website that hijack scroll and back button.