If you decide to give me AUTO regen, what's the purpose of sleeping and eating and paying for renting a room?
Just a minor bonus? And then ?

Roleplaying.

I guess there has to be something else...

Yeah, I wish there was a 'hardcoe' mode that required you to sleep and eat. =(

10% increase to skill gains isn't minor.

We need hardcoe mode like in Fallout: New Vegas

Dragonborn's should eat children only.

Food is very nice at low level as like potions you can pause game and eat a lot, Some food also give a low level and long time regeneration so it's smart to use before an hard fight even at high level.
Had been nice with more buff food.
Health regeneration is pretty useless in combat however you don't have to heal up minor damage, would keep it inn but probably reduce it.

This

+ places outside towns at night are more dangerous than during the day and as I play DiD I try to avoid them whenever possible.

+ some foods have additional effects when cooked

+ roleplay

This.

You Do gain bonuses from sleeping and being well fed.
you dont need to do this to play the game, but you get quite a nice bonus if you keep it up.

As if the game needed you to be more powerful.

Then again, I do think all the destruction complainers out there should sleep more so they get some more power into those fizzles.

I've slept maybe...twice?

Once to regain health, and once to get the dark brotherhood. And im a werewolf, so sleeping doesnt give me anything, so i more or less just ignore it now.