We all know at least one

meanwhile mages sleeping in enchanted robes of protection and sound sleep

Eh, I stick to "video game rules" for the most part in my campaigns. This lets the party focus on the more game-y aspects of DnD instead of the simulation-like elements. Otherwise, it devolves into a game of "simon says".
You didn't mention anything about putting your armor back on before breakfast. You've been ambushed, you're in your pajamas, and you're not getting to those eggs before they get cold. Roll initiative.
- I usually assume PCs did their mundane tasks that they should be used to, without needing the players to explicitly say so.
  Unless the player says otherwise, they take the armor off to sleep (because the game poses a penalty if they sleep in armor) and they put it back again in the morning, in the same manner I'm assuming they drink water, stop to eat when they are traveling, and take care of their needs, without the players saying so.
  That's just not the focus of the game
  
  DM: "So you've all been traveling for several weeks, anything you want to add about what you've been doing on the way?"
  Player: "Uh, I spot check?"
  DM, sighs, "Okay, roll for it."
  Player rolls an 18.
  DM: "Along the way you notice the hidden chest and find a latrine shovel. Anything else you're doing?"
  Insert 5 minute argument that it should just be a normal shovel and therefore it shouldn't be limited to just digging latrines.
  DM: "Now that that's settled, you can add your normal shovel that isn't a latrine shovel but can still be used to dig latrines to your inventory and answer the question if there's anything else you did, or maybe dug and then filled with something other than the dirt you just dug from it before filling it with the dirt you dug from it?"
  Player: "Oh, I know! I listen! Uh I rolled a 6 :("
  DM: "You don't hear anything and you all die from burst bladders and ruptured colons!"
  Insert 5 minute argument about which one, since it was unlikely that each of their bladders and colons burst simultaneously.
  
  I think some players have used a mithril chain shirt as a sleep shirt, which i think is technically legal.
- This. Role-playing shouldn't include the boring necessary activities unless they're no longer boring.
  If I wanted to run an ambush like that I'd have the players roll a generous save DC to see if they put their armor on already. Basically a DC 5, just to make it possible and maybe catch one party member for laughs. But not enough to be a serious barrier.
  
  Exactly. I was asked by my players at campaign start what the rules were for food, encumbrance, etc. I basically said that as long as nothing was going on that was out of whack with reality, we're not bothering with any of that. The only exception would be to avoid being game-breaking. Like traversing a desert on foot, I'd shift gears to track food and water. Or if they find a dragon's treasure horde, we're absolutely tracking encumbrance.
- That’s why I always take prestidigitation, to reheat the eggs afterwards
  
  I fully thought you were about to reveal some oldhead dnd hack where you can somehow don armor as a free action with prestidigitation

Martials are already underpowered enough without forcing them to give up even more of their meagre power.
- Eh, fighters are capable of dropping 6d12+96 damage at level 10. Assuming a 60 percent hit rate they're dropping an average of 90 damage, and a max of 168. They aren't underpowered, they're just forced into GWM/Sharpshooter and they don't get magical defenses without help. Which are big mechanical problems but not really power issues.
- You call taking 7 attack actions in a turn "underpowered"?

Laughs in Barbarian
- You can't spell barbarian without "bare ass naked".
  Well. You can. But don't tell the barbarians that.

In Pathfinder, you need a feat to sleep in medium armor. As for heavy armor, you're out of luck... barring homebrew or mythic campaigns.
- Obviously the solution is a set of medium armor pajamas just for sleeping in.
  
  "This is the gambeson my grandmother quilted for me; it's very cozy.'
- well you can sleep with armor, but you're gonna be tired since you didn't get a good night of sleep and have some debuffs
  
  Yes, the debuff is fatigue, which is also the debuff for not sleeping. So if you're a powergamer, you might as well just not sleep.

Iam right back from a larp. But players from a mercenaries company wearing full plates are looking for squire officially so people can discover that playstyle without buying a full plate armour. Unofficially, because with help, they can put their armour in less than 5 minutes instead of 30. So having squires would mean they can remove their armour without needing a lot of time to put it back
- 5 minutes in an ambush still mean you are armorless for the whole combat lol
  
  Which is technically the whole point of an ambush.
  However, for the players it means that when not expecting a combat, (tavern, camp) they don't have to carry 15kg of metal, without blocking the other players every time someone needs armoured fighters
  
  I attempt to negotiate with the pack of kobolds.
  Parleley, parlelellyleloooo, par le nee, partner, par... snip, parsley... parlay?

Not a problem. You wake up having recovered barely any HP, are still exhausted from the day before and now you're in an ambush! Hope the armor is worth it!

Every time Cloud went to hang his sword aside and lay down in bed in FF7

I had a character like that. He was a never nude and reasons for him being so were built into his character.
- I once doodled my Paladin's full plate as including a chastity belt with a big ol' padlock
  
  doubles as a codpiece as well!
  "look at the sheer size of my magnum dong, too bad you're not getting any!"

I just sleep in full plate, because keeping track of the AC difference is too hard (because I am lazy).

Not a bard obviously.