Actually what you just mentioned is velocity. If lots of transactions happen fast a small amount of market cap can come around and go around very fast, enabling lots of transactions.
Sure, but who wants to stand in the checkout line waiting for 10 minutes while your payment is confirmed ?
Right. For that you'd maybe prefer GeistGeld, which you get alongside your bitcoins, namecoins, groupcoins, devcoins, ixcoins, i0coins and coiledcoins when mining.
Or more likely you'd use a payment processor, a bitcoin denominated banking account debit or credit card or somesuch tool.
But again you are back to harping on velocity. Paper wallets in safe deposit boxes are low velocity.
-MarkM-