|It's nice to know how many items you have.
Example Char 1 hast 100 Rune Cloth on bank and 2 in Bag
Char 2: loots 1 Rune Cloth.
The Tooltip would show
Char 2: 1 Bag
Char 1: 100 bank, 1 Bag
this makes it very easy to track thing for professions.
Bagnon & Sanity both have this feature