Historical recreation currently seems to be the best rationale for a superintelligence to simulate this timeslice, although there are probably other motivations as well.

Much of the information from the past is probably irretrievably lost to us. If the information input into the simulation were not precisely the same as the actual information from that point in history, the differences would quickly propagate so that the simulation would bear little resemblance to the history. Supposing the individuals in question did have access to all the information they'd need to simulate the past, they'd have no need for the simulation, because they'd already have complete informational access to the past. It suffers similar problems to your sandboxed anthropomorphic AI proposal; provided you have all the resources necessary to actually do it, it ceases to be a good idea.

There are other possible motivations, but it's not clear that there are any others that are as good or better, so we have little reason to suppose it will ever happen.