Part of the joy of playing on PC is being able to run in whatever resolution you want. Especially if you're one of those people who like taking really, really pretty screenshots. 10 FPS? That's 10 gorgeous screenshots per second in some people's books.
If you're not obsessed with going into 200 FPS town, and you want to squeeze as many apocalyptic textures as possible into one screen, downscaling is the way to go. Fortunately, it's really easy to do in Fallout 4.