Not your screen monkey (he/him)
You can pretty much toss this one into the gameplay vs simulation pile. All of those decisions basically support making the fighter types better at doing what they should be doing from a game play perspective (tanking) rather than following the conclusions drawn from hit points being less meat than everything else and heavy armor impinging on defensive bonuses from Dexterity.So one thing I noticed about hit points is that back in the 1e DMG, Gary talks about how they are only partially "meat", and are more about your ability to evade serious injuries (dodge), luck, morale, and divine providence.
Going from this theory, I always felt that meant lightly armored classes that trend towards higher agility should have had better hit points all along- instead of a d6, why not a d10 or d12 for Rogues? Instead, the classes that already can unlock higher hit point bonuses from Con, who can generally wear better armor for protection (and you'd think would have a harder time evading hits*), get the big Hit Die.
*I'm not talking about the reality of mobility in armor here, but D&D has always modeled armor as being cumbersome and heavy, even though up until 3e, a guy with an 18 Dexterity got his full defensive adjustment in full plate, lol).
Choosing when to bend one way vs the other is part of the heart of good, effective game design that still fits with how people perceive fantasy stories to work.