My Fallout 4+ Suggestions:
Node map system with multiple DLC sized areas, diverse generated terrain larger than those in FO1/2 but smaller than POI's in between.
More places with higher level enemies like quarry junction. The vaults, caves, and above ground areas should all have a certain difficulty level to them.
The world(s) should be more varied. Cliffs, canyons, mountains, etc that are hard to traverse and dont have obviously marked paths. Zion Canyon for instance but more than just canyons. Enemy settlements should also be designed with more logic in mind and not so vulnerable. However, there should be hidden vulnerabilities that a clever player can sniff out. Also, less random npc's running around everywhere. I don't like running in to something hostile every few feet.
Points of interest should only appear on the compass if they have been clearly seen in the players field of view but at what distance depends on perception.
Enemy compass markers should only appear behind you if they make noise or if you have high perception. Same with in front but if they are in the FOV theres a bonus.
Explosive ammunition explodes when shot
More CC options. (muscle/fat sliders, topical details(scars, moles, etc.) hair length and more hair types and body hair.
Medicine should be a usable skill like FO1/2 but should be a menu like used in MGS3 where you have to treat each wound. So if you broke your leg, instead of just sticking a stimpack in it, you'd need a splint and bandage, if youre shot, you need a knife to get the bullet if its still inside, and a bandage. Oh and things like splints can be crafted.
Stimpacks (and other drugs) should do what they do in NV hardcoe mode but should be very rare, and have a limited number of uses before it becomes unsafe to use (over dosing.) However, you can have a chance based on endurance to not OD.