Some thoughts.
This is a role playing game system. By which I mean it does not come off as an hybrid, a board game, a video game, a story game, etc. It's a role playing game.
...
I would house rule it using a Holmes/Moldvay round structure and group d6 rolls right out of the gate.
My first reply was going to be "Dude, so which edition do you
actually enjoy?"... then I read your status.
The single biggest complaint I've been seeing is about hit points, and how they magically come back after a good night's rest. (Regarding basic, core mechanics. I feel if we criticize, these are the starting points).
So what are hit points? WotC seems to be a bit conflicted on this, if you compare the playtest to Legends and Lore. I've viewed them as how much punnishment you can take, not the overly drastic measures that some people might view.
If a troll tears off my arm during a combat, I'll be taking a crazy amount of hit points worth of damage. The loss of blood, trauma, etc will make me exceptionally weak. However, do I have to have my arm grow back in order to have all of my hitpoints back? I don't think that is the case.
In most combats, if you are reduced to 0 HP, it might just be reflective of the amount of physical punnishment your body has taken. (Think of a KO during a boxing match). Why can't a nights rest (food, water, relaxation) fix this?
I agree that my first example (arm amputation) cannot be fixed by a nights sleep. But I also don't think that 0 HP means that you have major broken bones or severed arteries.
That is my take at least. I'm curious how the "anti-full after sleep" camp views what a reduction in hitpoints means and why a night's rest cannot fix it.