I said traders/containers, not thieves/thieves/traders/containers. Wheres your problem? This is way more easier then unequiping stuff and then opening the locker. Besides, you could be able to barter with traders with items also in your hands - bottle caps. You guys ever played the game?
EDIT: List of uses:
1. Barter with items that are in your hands, including bottle caps.
2. Unload equiped weapons while bartering/using container
3. 75% safe bartering in NCR, all other 25% go to not equipped items.
4. other stuff I couldn't think of in speed.