The issue I find with the banks being the sole provider and processor of these Bitcoin certificates is that you could hold certificates denominated in just one face value. And one will need a lot of these papers in their wallet if they want to transact different amounts when buying stuff or services
I see your point, but it is not a big deal really
If we assume that Bitcoin banks would be interested in spreading their paper notes as much as possible, we should also assume that they will take care of this issue as well. The easiest way to do that would be to exchange their own bitnotes of one denomination for a few notes of lower denominations. On the other hand, if someone decides to deposit, say, 10 bitcoins, the bank could give them either 10 bitnotes each worth of 1 bitcoin, or 100 bitnotes each worth of 0.1 bitcoin
Do you think this paper Bitcoin certification system would work for buying everyday items like a coffee and a sandwich at lunch or movie tickets or a bottle of water? Maybe parking tickets? Isn't it more convenient to grab a metal fiat coin and pay with that and be on your way?
At least, people wouldn't be constantly whining then about Bitcoin not being suitable for offline transactions