Unnecessary, just like in real life.
But it's not real life and if u remove everything unnecessary u won't be left with much game...also bet alot of u anti smoking types take caffeine or alcohol...which is so much better.
The game has skooma which is akin to crack, why not a lil weed to puff in a pipe or cigar, tobacco plants where in the last game after all, it could even be part of alchemy making potion, paulices and prerolls.
Plus RPin an addict is interesting I've done it in every fallout I've played and would play the alckie skooma smoker if given the chance, choose the event to start or the reason you already are is great narrative in game.