There are likely many situations where this would be helpful, but mine is the following.
I made my wall o'SDBs on the first floor of my house while unpacking. I have a lot of them, so my first floor loads relatively slowly. Later, I built some more sparsely decorated floors which load faster. I'd prefer the SDB warehouse on one of the higher floors, but it would be a huge pain to move all the stuff one by one, so I'd love a "swap two entire floors" option, even if there was an iMG or even material charge for it.