First of all, the fact that you need such a code generator for the interface is a smell, not a good thing. To consume a REST service, you just need an HTTP client, possibly some authentication hashing, a url, and parameters and a json parser. You then get a hash.

The Web services I've used tend not to be super complicated. A handful of api calls tend to be used.

There's also versioning, which is handled well with a good url structure.

Also, the schema problem is more of a JSON vs XML issue. I personally use JSON because it's simpler for flatter data graphs. I also use JSON schema btw. XML does have the advantage of xpath (or css selectors) too.

But even in the REST + XML case, the XML is simpler than the XML + SOAP case.

Which brings up Content-Type. Rest can serve pretty much any content type in a way that's readable by almost any web-enabled client. Not so with SOAP. You need to have more software.

Basically, I can add these features on an as needed basis. REST is easier to work with right now and I probably will not need all of the features of SOAP. That's the gist of why it's less popular now.