It is hard to argue, for example, that we (real human beings) have been harmed by being brought into existence in a universe without a God who is listening; almost all of us would prefer to be alive rather not. The same would go for them: surely, their simulated existence, imperfect as it is, is not worse than not having been brought into the world in the first place?

It is not that hard to argue this. This is the non-identity problem.