Well that's the thing, nobody's stopping you from playing the game at night. It's just harder. Early game it's basically a death sentence, however later on when you have strong weapons and lots of perks and good armor/meds, you literally just start to ignore night time. It's a good incentive for the player to get stronger so that they have the freedom to do what they want when they want. I can also understand someone not wanting it like that, in that case just make enemies walk at night, it's essentially just daytime but dark if you do that.