I agree with the first point - it's very easy to Pass by accident and it's even worse when multiply items are in the active loot window. I'd suggest two improvements to the loot window:

1. (Mainly for the controller users) After selecting the item have the option to:
- Press X to Need
- Press Triangle to Greed
- Press O to Pass
- Press Square to "Keep" (see point 2. bellow)

2. Add the "Keep" option which will be evaluated ONLY if noone else selected the Need or Greed on the same item - this way you can "politely" opt for the items which would otherwise end up in "Unable to obtain" status and become lost.