Having to change maps simply to make floating bricks isn't useful in any of the circumstances you'd want floating bricks in - to make a spaceship in the Bedroom and load it in another map could just as easily make it embedded in the floor. There's an easier method involving another player clearing their own bricks under yours, leaving yours floating. Or just make a tool which deletes the object instead of the general "Destroy" functions which check the brick tree.
If you hammer one brick on that the whole structure collapses, so having them float isn't too useful anyway.