With Code-First approach, developers usually dont write WSDL and let the framework take overhead of generating it.
As per your suggestion, specifying wsdlLocation in endpoint would require generating WSDL and I personally feel that it would defeat
the purpose of code-first approach.
If WSDL is created for code-first approach, it would also require developers to keep it upto date with java code, which might be error prone.
Hence the simplest approach would be to use the schemaLocation and specify the XSDs used for JAXB value object generation.
This also saves from efforts spent in maintaining upto date version of WSDL with java code.

Anyways thanks for pointing to the link.

http://stackoverflow.com/questions/2231779/cxf-and-validation-schema-restrictions-ignored