But do you think the web services core can be complete without one of the Reliability standards? You cannot reliably use SMTP for instance, and in many HTTP contexts some other form of reliability than HTTP 200 OK is highly desirable too, so this one seems a basic as security to me.
Interesting, and subtle, question. On the one hand, an awful lot of commerce happens over HTTP. On the other hand, there's a lot of reliable messaging (such as IBM MQ) used inside business organizations. The biggest thing holding back reliability is that there are two standards. Let's see them reconciled, and added to the stack. That's not inconsistent with the column, since it's not a WS reliability spec won't change soap, xsd, schema, etc.