It shouldn't be dice-based damage for falling long distances at all, it's a nonsense to use dice for that, because that's simply not how falling works, and the more extreme examples we go with, the more obvious it becomes.
It should make it a saving throw that's harder based on how far you fell, probably with Advantage/Disadvantage depending on hitting water/loose snow/etc. vs. solid rock/stone (this is fantasy, it doesn't need to be super-realistic, just make sense in the fiction, which the current approach definitely does not).
If you fail the save you're reduced to 0 HP, and are having to make Death Saves etc, pass you're prone and stunned but miraculously don't take damage. I could see something more generous for falls of less than 50ft (maybe extend it to 100ft for the sake of heroism, like 50% of current HP and prone + stunned on a fail, lose 10 HP on a pass). The trouble is with D&D's combat - this would make dropping someone far enough into a save-or-die, which would mean fighting most big monsters or serious opponents, you'd really want to drop them - obviously Legendary Resistance would work on this save though so I'm not sure that would be a huge problem. But I do think if falling was reworked this way you'd probably want some class/subclass and monster abilities to make the save easier and/or negate damage/increase distances. Which is probably why they haven't done it - it would take actually considering quite a few rules.
Terminal velocity means infinite damage scaling isn't reasonable, and people have survived falls of any height on to a variety of surfaces (always more due to luck than judgement), and just having low-level people always die if they fall like, 50ft is also not great.
