here is the main problem with "hardcoe" or "survivalist" mode
It was (lets be blunt) half arsed in New Vegas, and more or less just cluttered the hell out of your inventory with all the crafting crap. between the food items and stimpacks it was all to easy to cheese a "hard" fight by simply stuffing your face just before you pulled the trigger beforehand and then just blitzing it. and since you did that to heal, you usealy did not need to eat or drink... ever.
there was no difficulty or challenge added beyond needing to cherry pick your loot, which you end up doing anyway hardcoe or not.
now lets continue to be blunt. I would love to see a survival mode that would be a bit more useful, and not so Fracking broken
For example Food/water would negate hunger/thirst over time, and maybe provide a slight boost to normal healing,but would be restricted, no more stuffing your face with 2-3 drink items, and enough food to make the 72 Oz challeng over at Big Texan look like an appetizer plate for a baby feild mouse for example.
Unfortunately, developing a hardcoe mode that is not half assed takes work. it takes time to create the game code, and time to test and balance the game code so it does not end up being basically useless while still providing some kind of actual benefit.
I suspect they realized they had a choice to make.
Spend time developing a Proper hardcoe mode with Weapon degridation.
Spend time Developing a full blown mod System that covered everything weponsisable.
if that was the choice, Im kind of glad they made the right one here.