You approach a Box, you have 25 wood, 125 sand and 30 crystals... and 20 more like that in that box.
they can all stack to 250
so instead of dragging eveeeeery siiiiiingle item from your inventory to your bank for minutes, there is a little button "Quick Stack", it takes all the wood, sand and crystals from your inventory and stacks them into the bank box to the appropriate stacks until it hits 250.
one click all done
-> WANT for STO!
(and if the accountant needs a $ reason behind it... it would make the Bank Slots you sell in the C-Store a lot more interesting if the Bank would be less micromanagement.)