As Ive played fallout 4 (305 hours as of writing this) I've thought of some features that would improve the games enjoyment.
Deployable weapons:
By this I mean mortars, 50 CAL MGs, MG 42s, 50mm anti tank guns and plasma canons that must be placed on the ground like a turret before using. Then, like the Vertibird minigun you can "board it" and use it to set the world on fire. This would add more big guns with a drawback and add all new play-styles and tactics.
Weapon jamming system:
When I looked and the weapon concept art I noticed that the pipe weapons had reliability ratings next to them so I got to thinking what if sometimes Weapons would Jame making you have to reload again or do a short animation before fire again? So pipe weapons would jam all the time. Revolvers, energy weapons and breech loaders would never jam. Bolt action would sometimes jam and gas operated would jam now and then. Probably best if this was toggleable or only on survival.
Parkour system:
No, not a full on game changing system like in assassins creed just a simple one. Maybe the rapid reload perk could be merged into gun foo and replaced with the parkour perk. Level 1 makes you jump higher and vault over wast high objects well sprinting, level 2 lets you climb chest high objects like barrels by standing in-front of them and jumping and level 3 lest you catch the edge of a ledges the fall short of and pull your self up like in platformer games.
Burnable landscape:
Molotovs and flamers set old tires, wood shakes, grass and trees on fire for a short time burning everyone nearby (good idea seeing that's the hole point of a molotov and all).
Deployable barbed wire:
Just a side note being able to put up short (destroyable) lengths of barbed wire would be a useful tacit of slowing down hoards of ferals.
Controlable Tank turrets:
Simple the tanks found around the wasteland can be moved to settlements then boarded like a Vertibird and used as turrets to destroy everything like a boss
PS. I have reading/spelling dyslexia but I tried to make it readable.
PSS. this sights spellcheck dose not recognize the words Vertibird, minigun, platformer, molotov, toggleable or ingenral any word with able at the end.
Singed possibly adoring fan.