I do find those kind of mechanics "entertaining"...like you having to go poo, sleep, eat...not only battle-related content are fun. I do would love having a "Sims mode" here as soon as it had a purpose, like in the above mentioned games. Having a certain mechaniscs "just to have" can be bad (like the current repair FFXIV system), but having it with a purpose (even if hidden) behind it makes ths kind of immersive mechanics 100% valid.
Having to poo in a game is fun...?
I don't need to add anything in this, it destroys itself effectively.

In Baldur's Gate you had to sleep from time to time...your character do would get overly exausted if you don't sleep AND you had to sleep in a proper place (even thoug you could do it everywhere) if you didn't want trouble.

In Digimon World you had to poo from toime to time...just like baldur's gate, you could do it anywhere but you should use the correct place if you didn't want trouble.
The first game might be fun but I am 100% sure that it wasnt the "having to sleep" system that made it fun, I mean c'mon now really?

The second game sounds like a pet game, sure in a pet game the most realistic the better, but FFXIV is not a pet game and I dont want it to be a pet game, whats so fun in sleeping and having to go to the bathroom anyway?
If you HAVE to do somethig that it's not fun in order to bring the rest of the game to the normal levels of fun then why have the system at all?
It's still gonna be the same game after all with the exception of not having to do unessessary stuff.