It seems to me that we, as a species, would be a lot better off if we didn't remember so much. I've heard people say, in response to the sentiment "forgive and forget" that they can forgive but not forget, and part of me wonders how complete forgiveness can be without some forgetfulness.
Memory is a huge part of who we are as a species, and as individuals. Our memories shape us and inform our personalities. As the sharpness of memory fades, painful experiences are dulled, joyous experiences are softened, and middling experiences are often forgotten.
My memory is important to me, and I hold it close, which is probably part of why I can hold a terrible grudge. I'm trying to learn to let things go more easily, and I'm doing pretty well, I think, but it's an interesting contradiction, to try to cherish the good memories and let go the bad ones.
In a larger social context, we're not good at letting go of those bad experiences. "We Remember", "Remember the Alamo", etc -- we hold national grudges as though doing so will preserve us for the world's memory. Or something crazy like that.
Let it go. Easier said than done, or even desired, I guess.