In this thread at Charlie Stross's, it occurred to me that social outrage is a constant, but that its content is infinitely variable. You could almost call it the principle of the conservation of outrage - outrage can neither be created nor destroyed, but only transferred from one object to another. Addiction to drugs or drink has transitioned from being a sin to being a medical condition. Mental illness is doing something similar. Sexuality, for several whole generations, is a ship that has sailed.
But you'd be a fool to imagine that the outrage has gone anywhere. It worries me that, for example, the revival of what Paul Krugman calls New Austerian economics is really explained by the need to be outraged at somebody - the surplus of outrage has been directed at the victims of financial misfortune, who are always in ready supply. Of course, the fact that it went that way is interesting in itself and tells us something about the functions the pool of available outrage performs.