Many long time residents of San Francisco are both shocked and fascinated by our changing skyline. Once Sutro Tower, The B of A building, the Transamerica were kings. Now we see them dwarfed by high rises that seem to come shooting up directly from the bay.  The logic of high rises is fairly obvious. San Francisco suffers at once from a housing shortage and from space to put it. Thus vertical construction makes sense. What makes less sense...more.