Who Cares Re Bygones?
It really is easier to get forgiveness than permission:
In 7 studies, participants judged future bad deeds more negatively, and future good deeds more positively, than equivalent behavior in the equidistant past. In addition, participants thought that future unfair actions deserved more punishment than past unfair actions, and were more willing to sacrifice their own financial gain to be treated fairly in the future compared with in the past. These patterns were explained in part by the stronger emotions that were evoked by thoughts of future events than by thoughts of past events. (more)
This is a form of hypocrisy, in that we pretend to be more offended by the fairness or morality of actions than we will actually be after they occur and can reward or punish them.
More strategic than hypocrisy.
Derek Parfit has done a fair bit of analysis of time-inconsistent morality; it's appears to a general phenomenon, not limited to examples where we can reward or punish others. For example, suppose that you are going to have a surgical operation that will cause you a great deal of pain, but will also cause you to lose your memory of the operation the next time you fall asleep. Most people will, upon waking up, be much happier if they find that the operation is done, than if they find out that it is about to occur; the same is true of a positive experience. People tend to judge things more extremely before they occur than after.