Well, I can think of one huge reason not to. If you misplace your Visa card, for instance, you can get a new one without having to also get a new Mastercard, video store card, library card, etc. If they’re all in one card and you lose it, then you’re back to the lost or stolen wallet scenario.
Anyway, what the Protean Echo does is exactly that: combine all of your cards onto one, saving you space in your wallet. It works in tandem with your phone through a dongle, which allows you to scan your cards’ magnetic stripes. The cards’ information is then stored on your phone, and you can choose up to three at a time to load into the physical Echo card in your wallet. When you want to buy something, all you have to do is press a button on the front of the Echo, choose which card you want to use, and swipe it as you would a regular card.
I’m still not convinced. But it does have definite potential, should some issues I can see coming up get worked out. Like, what if you lose it? How secure is your credit card information on your phone? What if a retailer won’t accept it as payment because it looks absolutely nothing like the credit card you claim to be paying with? There’s also the thing where your physical card has your signature on it, and I’m not sure retailers would accept a digital facsimile thereof.
The plan is for this to launch on Kickstarter this winter, and expected cost will be between $80 and $100 US.