A great idea and we can see what the benefits would be. However, in practice, it's not something that would work in Vice City I would say, due to the physical size of the islands.
The bank is in a decently accessible location and giving other methods of retrieving money may mean that less people end up utilising the bank's service, although the 10k cap might get over this.
Perhaps to get over this you could introduce cheques when undertaking large transactions between players (in person) if looting is a concern. At the same time, the handing over of the cheque could be roleplayed and /wire made use of, although in some situations this may not be so ideal.
The situation of /c loot in the upcoming server version(s) may yet to be cleared, so who knows, we may not have to worry about it at all. : )