I feel that the fact that our primary and secondary weapon slots are divided, (Arc, Solar, Void, being the secondary, Kinetic, Stasis, Strand being the primary), limits build crafting by not allowing a primary ammo and special ammo of either at the same time, ( tessellation being an exception to that specifically ). Why not allow the change so it's not primary or secondary, but Weapon 1 and Weapon 2, element wouldn't matter could go full strand, stasis, void, arc, solar without the need to have an osmosis/permeability weapon. I also feel weapons with random damage types similar to Ex Machina in D1 where it could drop solar, arc, or void except a stasis weapon with incandescent, next drop could be a void wagon with headstone or hatchling both being the same weapon capable for separate builds. It no longer locks out certain weapons from being used but incorporates them together so those builds that matching the damage type gets the most benefit can prosper.