To some extent i agree that the smaller sets are more mobile, and allow greater playability, and i honestly doubt that TLG will ever design this , but it would be an awesome repository of tan bricks. Also, it would be at least as usable as most of the UCS line (ISD, the Millennium Falcon especially, etc), none of which had interior, since a UCS Hogwarts would most likely have some form of interior, or removable levels. If it was designed well, it could easily be a great set.
Just my two cents... (or if one is ever officially released, $300+ )