One problem I find is that its really hard to make a profit trading. In the old system, caravans, the time to travel, and the soldiers needed to protect against vagabonds, just didn't allow for much profit to be made. The only reason to trade was to help feed your realm's city, or to transport food across to another realm and help them feed their cities. Of course, this was just in my experience with trading.
I think it's much easier to make profits now, mechanics-wise. Market-wise, that's another issue though.
Some kind of system to "trade" resources may be possible. But the idea is to simplify the system, and get rid of the extraneous bother and complexity. We want it easy, and without much player overhead.
Communal resource management is one way to reduce the burden of new resources, while giving the banker something he can actually do for once, but I think that these resources should be produced in nearly every region, albeit in different quantities. If by civ-style, you meant that one tile (region) has all the resource you could possibly need and the rest don't have any, then I wouldn't consider that to be a good idea.
