You can bank the Items wich you buy with AP, i see now problem there
Since players can have characters in multiple factions, this wouldn't work. You could earn a bunch of AP killing EP and then spend the AP with your EP alt - kind of wacky IMO.
(Now, if they did what I think, and bound entire accounts to one faction, then I'd be all for sharing AP)
The other issue with transfering AP is it's very easy for players to go farm non-vet campaigns then transfer the AP to their max VR characters and buy end game gear to use/sell.