Because we won't do better parsing of XSD and its Java represetation than Xerces. I am sure that's one of the reasons you are using it as well. And JBoss WS, BTW, is one of those projects using XSD-based bindings, at least it used to. Otherwise, there might be uses in the AS.
In any way, I can binary-separate the XSD-based binding part (which should be done anyway) and try running the AS to see what fails, if anything.