From what I understand 10 minutes was chosen as a best guess based on p2p network propagation time for very large and dense networks.
I think this is a good point, so far as the issues about how the time interval has been selected. We really don't know how large Bitcoin is going to get, and my personal guess is that it will be considerably larger in terms of the number of people involved than is even using Bitcoin at the present time.
I know it is discouraging that ordinary folks can no longer realistically be able to mine Bitcoins using an ordinary computer, and expect to "discover" Bitcoins in a short interval. I've expressed concerns about this very issue in the past and it went upon deaf ears then. I've since learned a bit more about the Bitcoin architecture and realize that it is a difficult to intractable problem except for mining pools and other strategies to apportion out at least some Bitcoins to those who want to participate.
On the whole, Bitcoin does a substantially better job of verifying transactions than the Federal Reserve does for check transactions, or for that matter even ATM transactions. While check kiting is much, much harder to do now than it was in the past, it still can be done, as can the reverse in terms of banks holding money for seemingly impossible periods of time (up to a week or more) when somebody screws up. Knowing that a transaction will generally be "confirmed" with 5-6 blocks incorporating that transaction in a hour is to me a pretty good result, if you consider the alternatives that exist elsewhere in the banking community.
Most retailers, I would believe, would be ecstatic to know that a retail transaction was completely confirmed as theirs within an hour or less, particularly that "charge-backs" could never happen after that. Even if you have to wait a half hour for the next block (because of random events happening) it still isn't the end of the world.
The worst part, as mentioned earlier, is what happens when mining activity drops off considerably. I've argued that the re-adjustment algorithm needs to be modified somewhat, and that is the achilles heel of Bitcoin, as it could have some more generalized adjustment algorithm that isn't so coarse. It does stops certain kinds of attacks by being that coarse, which I won't go into now but that is something to consider if you want to complain about the readjustment interval.