I find that a lot of loot is hard to pickup.
Arrows in particular have a vary small "active" area when you try and mouse over for a pickup.
Further, loot in boxes and barrels can be "in" the bottom of the box, or sometimes actually imbedded in the floor.
How about making the active mouse area on the loot bigger for easier pickup?
How about making the drops from crates and boxes "auto-loot" themselves into your bag?