[unquietcode]

It's worth noting that in complex systems, forgetting can be just as important as remembering. The ability to evolve and change is in part predicated on the ability to selectively forget some elements that are no longer helpful. As another commenter pointed out, some aspects of our society's cultural memory are, probably, best left in the past, if preserved at all.

[notabee]

Knowing what should be forgotten requires either foreknowledge of the future or relies on inaccurate predictions based on current assumptions. Thus the less information of uncertain usefulness that is retained, the more that those assumptions dictate what will be considered useful in the future without having to rediscover things entirely. That limits adaptability. Just try to imagine how many things were invented in the past that weren't seen as useful at the time and had to be rediscovered later. How many ideas were lost in the Dark Ages, for instance, because they offended religious sensibility at the time? If there is capacity to retain information in an organized way without undue cost, it should be retained as a hedge against future uncertainty. No single generation of humans should be trusted to make such decisions without being unduly influenced by the biases of their time.