For one, it is a huge step forward from existing payment processor communication. Most card acquirer software is vintage 1997, either by sending large amounts of unstructured text over the wire, or parsing through XML, or dealing with error codes that mean nothing from acquirer to acquirer. Switching banks, for example, is such a massive pain in the ass because you essentially have to rewrite your entire card processing code from scratch. Having this easy-to-use API will encourage competitors to play catch up, and it is a pretty good selling point for using Cybersource.
Second, and you can make an argument about monopolies or whatever, but PCI is essentially controlled by Visa and Mastercard. It is entirely possible for Visa to strongarm mom-and-pop-acquirer to play by this API, and then (hopefully) add the public tokenization later. For e-commerce, storing and transmitting only tokens is huge, and goes a long long way towards mitigating the severity of these massive retail breaches.