Has anybody seen these "mini-credit-cards"?

My bank just sent me a new debit card (despite the fact that my old one doesn't expire for a year or two), and along with it, this "mini-card". It's about 2/3 the size of a regular card, and has a hole that you can use to put it on your keychain.

Now is it just me, or is this a really, really stupid idea? Before, if you lost your keys, then it was mostly just a hassle. The only way it would cost you a lot is if (1) you didn't have any copies made, (2) If you had a garage or car remote on it, and (3) If you have one of the newer cars where the key isn't really a key, but a piece of metal with a microchip in it, in which case you have to pay like $50 to get a new one. Now if you lose your keys, you can lose the contents of your checking account in the same stroke! (Not to mention that your credit history can be ruined.)

Even putting that aside, what's the purpose of this thing? I assume you can put it through most card readers (the sliding kind, anyway), though not the ATM or any other reader which sucks up your card (as they warn you in BIG RED YOU'RE-AN-IDIOT LETTERS). However, if it's attached to your keychain, this may well prove difficult. In any case, I don't see how this is any more convenient than your regular card, except maybe that you have to make fewer finger movements.