We can attribute much of nudity's power to the fact that we're hardwired to drink it up.
According to a 2011 study from the University of Tampere and Aalto University in Finland, our brains boost the processing of sexually arousing signals and actually access nude and clothed bodies in different ways.
Sexual or potentially sexual images process faster. Our brain is like the bouncer at a fancy club who let's the hot, sexy people skip the line. And as our basic genetic mission is to breed and propagate, that makes perfect sense.