This is difficult topic, as for some "RPG" is really just G, without RolePlaying in it. And then hardcoe is just making the game difficult for the player.
For me, the RP in RPG isn't about game difficulty or the game forcing me to eat, drink, sleep.
In spite of the fact that many consider things like having to eat and sleep "serious roleplaying," I don't. To me, "serious roleplaying" is the act of creating a unique, detailed, complex character and "playing" that "role."
I second this. For many things, I can roleplay those even if the game doesn't ask for it.
Realism != immersion.
Options for realism are great, but it's not immersion, Realism is often making game hard for the player who plays the game, which has nothing to do with role-playing, it's just "being better" playing the game. It's OK to have options for those who enjoy "beating a game". This is also something some consider "hardcoe".
With role-playing it should be more about the skills of the character in the game, not the skill of the one who plays the game. And as mentioned, as long as I can choose to roleplay and do something (e.g. eat, drink, sleep at the inn, etc), the game does not have to force it.
More important for immersion (from roleplaying point of view) are the things on screen/graphics
- dynamic weather (and having NPCs react to the weather too)
- option to disable (parts of) "computer HUD" (e.g. have compass as an item I can look at instead of one on the screen),
- option to have no quest pointers,
- option not to have digital clock,
- allowing me to walk and look around without every living creature reacting only to me (and always attack on sight if not peaceful),
- having wild animals that don't attack the player (or only attack if the character is a threat to their nest/offspring/etc)
- pick flowers and place them to the window-side table at my house
- sit to a table at the inn and look out the window while sipping tea
- "immersive" gear in game, even if it's just a cloak on the back that looks like backpack