The problem is in spatial organization of all this. Having a central node that grows both upwards and downwards is extremely confusing. And more to the point, having other sorts of traditional map-style representations of this where there weren't long lines between various groups of rooms, is pretty much impossible. Well, I won't say impossible -- there might be some way, but I've sunk several days into it and could not find a way that was remotely as compact or clear as what is in the game now. As in, nothing else would even fit on the screen all at once. Of course, that was back in the days when most buildings had 100-1000 rooms, so that didn't help.