I love this game, but there is 1 thing which really annoys me a lot and that is the shared (X) button to both loot and pickup weapons, time and time again I end up picking on random weapons which are worse than what I had equipped,...

My suggestion is: Change "Switch Weapon" to have its own button such as (Y)... so
(X) = Loot Ammo
(Y) = Pickup/Switch Weapon