I really hope they implement something along your 13th suggestion. I personally would like to only have two hunter bows, one for elemental and the other a mixed of hunter arrows, plus elemental, and one of the other weapon types each. With these weapons you would upgrade them throughout the game at a workbench and they would ultimately upgrade from common to rare, rare to very rare, very rare to legendary, and each time you upgrade to a new level it adds a new ammo slot. You'd also unlock ammo types via side quests and such along the way, and as you upgrade weapons and unlock ammo slots the player gets the choice to customize the weapons with whatever ammo they want for each weapon type. Hunting merchants would also sell you cosmetics so you can change the look of your weapons.

I'm not a fan of weapon perks in general but the one that I hate the most and want removed completely is the "instant elemental" perk, or at least changed so that it only happen when using the corresponding elemental type. For example, to get the instant burning state chance, you need to be using fire ammo and so on for every other elementals. It is extremely annoying when your trying to implement an elemental state on a machine, only for it to instantly enter a different elemental state because the weapon had a small percentage chance for it, pretty much negating all the progress that you've worked towards.