Wait, then what DO artists draw for? You crazytype, I tell ya...
... hm, maybe mentalbation, culminating in braingasm? I know it works for liek-reely-kewl-ideeahz, but, yeah, maybe, just maybe, the sheer beauty of a pic can give an euphoric, near-erotic, pleasure.
Though, it does sound an awful lot like how girls respond to a hawt guy's face.