There is an essential ambiguity for this discussion between "pointless" because subjective anticipation won't allow you noticing, and "pointless" because it doesn't optimize goodness as well as other plans do. It might be pointless saving people in the past by building sims, but probably only for the same reason it might be pointless reviving the cryonauts: because there are even better decisions available.
To clarify: I already accept the objections about "burdensome details" and "better plans". I'm only interested in the subjective anticipation angle.
ETA: sometime after writing this comment I stopped understanding those objections, but anticipation still interests me more.
This is our monthly thread for collecting arbitrarily contrived scenarios in which somebody gets tortured for 3^^^^^3 years, or an infinite number of people experience an infinite amount of sorrow, or a baby gets eaten by a shark, etc. and which might be handy to link to in one of our discussions. As everyone knows, this is the most rational and non-obnoxious way to think about incentives and disincentives.