Is this true human nature coming through freed from artificial constraint? IMHO it's the contrary - social feedback is part of what makes us human, and short-circuiting that feedback gives us a temporary holiday from our 'selves', for good or ill. Like getting drunk.
Though I sometimes wonder whether I behave better online than I do in person. I have many faults in RL conversation - interrupting people, getting cross, getting fidgety - which I try to rein in on the Internet nowadays. I adopt this social persona as communicator and I have an investment in behaving in a faintly civilised way, in order to remain embedded in a milieu - livejournal and associated blogs. So no online Saturnalia for me.