<fileDesc> and <biblFull> are meant to be parallel in structure, in that you can plop a fileDesc content into a biblFull. There are differences between them in the memberships of attribute classes that they claim:
att.declarable.attributes,
att.sortable.attributes,
att.docStatus.attributes,
are on <biblFull> but not <fileDesc>. There is no reason for <fileDesc> to be declarable or sortable since it only appears in the header. However, having a @status on <fileDesc> might be useful. (e.g. to indicate that the fileDesc itself is a 'draft' or something, while the rest of the document is at a different revision status).
Might this argument (need to indicate its draft or other status) not be applicable to just about any element though?
At face-to-face meeting in Providence 2013 Council decided this was not to be fixed. Closing ticket as won't fix.