I think it would be nice to have Exceptions thrown whenever an annotation is misplaced (doesn't make any sense).
an @Table doesn't make sense with a @MappedSuperclass. In order to make a developer's life easier it would be nice to throw an Exception (or at least warn him) to find the error earlier.
But this seems like a lot of work.
We already do this all over the place. If there are specific conditions that are missing, let's discuss one-by-one, rather than 1 blanket ticket.