I always proposed on the Bethesda forums in the Fallout 4 suggestions thread that was going on for years that if we have to keep being FPS then at the very least use the world map of Fallout 1/2. Basically, imagine if cities in Fallout 4 were the size of FNV's interior streets (The Strip, Freeside, Westside) or the size of The Pitt and then there'd be locations like Big Mountain, Zion, Point Lookout but a bit bigger so that it takes you longer to explore all of it. And finally, there'd be locations like Golgotha or Toxic Caves from Fallout 2 in the vein of the first mission of Broken Steel where we travel to this small secluded area that is basically the entrance to a dungeon.
Combine those things and we'd get big cities/towns to explore, loads of very varied and unique exploration areas and even secret dungeon areas you can only access on the world map if given the coordinates or if you manage to find it on your own.
But nope, Bethesda wants to impress us with their scaled down cluttered themepark worlds.
So many good suggestions came out of those threads and not a single one was listened to.