All you have to do is re-enter your house and walk out. If your exit is "blocked" for whatever reason, enter your other house and exit, if both of your houses have blocked entrances (and you can't be bothered to move whatever is blocking it for a moment) then you can unstuck me, if you don't want to unstuck me because you're in snowtown or something, THEN I suppose an "Out" button could have a purpose.
But that's just one more icon on my screen taking up space, and most people wouldn't even need it. If anything, an "exit house" option on the house/GH menu screen, would be preferable.