Classically a PC gained the ability to withstand one more hit per level, up to name level, and then HP gain slowed down after that.
So a 10th level character would be able to fight with 9 arrows in him, which is heroic but not completely unreasonable.
50 cent survived being shot 9 times.
I likewise don't consider falling damage to be so nonsensical when HP scaling is kept in check.
It is possible, though unlikely to die from a 10 ft fall, and possible, though unlikely to survive a 60 ft fall, particularly if it's down a ravine or waterfall as is often the case in a game of D&D, rather than the experimentally controlled straight drop onto concrete as people often seem to assume when discussing this issue.
Toning down the scaling solves many problems. It is a Good Thing.
(You don't necessarily need to increase defense scaling to compensate for reduced HP scaling. You just need to reduce damage scaling.)
You are absolutely correct on what you say here. The only real issue though is one of amount.
50 cent getting shot nine times and surviving or a heroic fighter being embedded by nine arrows and continuing on are possible... but
rare. However, in D&D the way the game itself works is that a fighter takes nine arrows to the chest, survives, gets touched on the head by a Cure Light Wounds wand 15 times, then gets back up and within 15 minutes gets into another fight where he gets embedded by nine arrows
again and somehow survives it
again.
And this happens over and over and over.
It's ironic that for all the talk of finding ways to cut back on the '15 minute work day'... the game instead sets up a situation where it expects warriors to get wounded and on the verge of death 2, 3, 5, 10 times
in a single day. How ridiculous is that? I mean, just think about the
psychological issues of being severely injured and in unimaginable pain several times a day (even if you then get 'healed' right afterwards.) Ever been burned alive? I haven't... but I imagine that if I was once... I'd never want to go through that agony again. And yet our D&D characters sit right in the middle of fireballs that drop them to 0 how many times during the course of a campaign? They get caught up in traps that make the
Saw movies look quaint... and yet right before they die the cleric runs up, pats him on the head, and removes all the physical injury in a few seconds and the guy somehow says "Whoa! Glad that's over! Okay, onto the next room with the 15 orcs with battleaxes!", completely forgetting how much pain and suffering he was just in.
This is why we make the claims that hit points shouldn't be actual physical wounds (ones that require magical healing or week-long bedrest.) Because just as 'immersion-breaking' the healing surge mechanic is... the 'attack damage cause physical wounds' concept is just as ridiculous (if not ten times worse).