It isn't the only issue i have with FONV/Fo3 and i admit FONV do far better that Fo3 even on that point, but i find that those games lack of focus/efficiency.
More than half of the locations are useless/generic. Even it there is more variety in FoNV, you spent countless hours visiting generic places like Abandoned house #17, Cazadore's nest #7 or Ghoul's toxic pool #59. I already have the "125 discovered places" achievement, but seem that there is at least 125 other places to visit (picked explorer).
I admit i don't have to visit all those places and i probably won't on next playthrough, but i like to complete RPG games, particularly in the Fallout Universe, so i make sure to visit everything, talk to everyone, loot every chest, try different quest outcomes at least once. But right now, all these useless places leave me a very bad taste. I wonder how much time they spend building all this uselessness and how much time i spend being disapointed by them. I would rather have a twice bigger strip that any of these places. Hopefully, i will have better time with "choose your faction" related quests and DLC. (the latter having generally better efficiency) All the (not choosing your faction) quests that i did were good and the NPC i talked so far were pretty satisfying. And, for the first time since decades, the setting feels really fallouty.
In a way, i feel better in the more focused Metro universe, it's a welcomed escape from those poorly used open-world.
(not that i hate open-world, just that it doesn't fit in every games)