Right now, developing your own paid rest service is a huge pain in the ass. You have to sign up to process credit card payments / paypal, manage sales and so on.

Because of that it's possible that many people don't consider building them (and some people do it for free, but it's another matter).

If there is a simple system to charge for such services, we might soon see a situation in which there are literally thousands of available services. And it's not a choice between using CC and using Bitcoin, but a choice between using the few services that handle CCs, or a plethora of services that use bitcoin.