Depends...

Can you expand your bank a considerable amount? Because if I was limited to just one bank for all of my characters that would suck!

My bank is full of crap, and thats just for one character. I have too much crap to cram in there for all of my characters.

How else can I store my useless crap but to have bank alts?

In EQ it was two sections in the bank. One set of 8 slots for the character and his cash. One set of 2 slots with cash available to all characters.

One of the major (the most?) draws to an MMO is player interaction... eliminating gold transfer would basically eliminate the economy and take a lot of fun out of the game. This seems like a very unworkable change to me.

I mean, the whole reason all the professions relied upon each other in vanilla was to force player interaction. They've since changed their direction a little bit, but I really can't see them moving that way.

I think player interaction is coming more from raiding than tradeskills. I buy anything I want "made" on the AH already.

When I say all characters share a bank, I meant a bank account (the money). The bank slots for items could be per character. It's not like you run around with your money in your pockets in WoW, like you used to in EQ, so it's just a "credit" system anyway. There are already mods that tell you how much gold you have across all accounts, I seriously doubt it would take more than 4 minutes* for Blizzard to come up with some programming to link all of your accounts' money.

* And by 4 minutes, I mean 6 content patches.

Ah, the days of dying in the Commons tunnel with too much plat in your pockets...