I'm also not clear how the recipient supplies their info to the sender's bank. If I don't have an ING account, how can they verify that I'm me, and not someone else who's pretending to be me in order to intercept the transfer? As I recall, when I've done wire transfers, I've always been given the account info of the recipient for me to provide to my bank (but I haven't done this very frequently).
Edit: I just saw your other reply where you describe the ING app. I guess that works, but it's rather unfriendly. I'm always a little wary of high-security stuff (such as money transfers) that depend on email, too, but that's also an issue for Dwolla and probably a lot of the other payment startups.
But how is that any different from a credit card number? I have all my bank info in my pocket, right on my Maestro card. No expiration date, no CVV code. Just an account number and a publicly-known bank number. If I'm authorizing a direct debit, that's all I have to enter.
The 6 digit sort code is unique for the bank branch across all UK banks, generally the branch on record for the account (most UK banks use the sort-code for the branch the account was opened at). Unless you happen to mistakenly enter an account number and sort-code that matches, and you manage to mistakenly enter the name of the account holder for that bank account, they'll usually catch it.
The situation is similar across Europe, so if this is a problem in the US, it's a problem of the banks own making, and one easily solved the same way it was in the UK: By adding a sort-code, and matching on the name as well.