On the hjkl thing, I think it's also good to explain why it was a good idea that the ADM-3A used hjkl, and that's because it allows directional navigation (an extremely common operation) without moving your fingers away from their "home row" position.
So vi/vim use those keys not /only/ because some old terminal, but because some old terminal used those keys /and/ there was a benefit to it.
Having my fingers leave home row as little as possible is vastly superior to reaching for arrow keys and having to reposition my fingers on home row.
With vi that made immediate sense to me. Switching to HHKB layout made even more sense, because I now can reach both CTRL and backspace easily without lifting my fingers from home row.
I did change my keymap even further, so that arrow keys are mapped to fn+hjkl. This way, I can navigate everything just with hjkl (:
So vi/vim use those keys not /only/ because some old terminal, but because some old terminal used those keys /and/ there was a benefit to it.