Simulations might be of limited utility (given limited computational resources), but they'd certainly help.
Without simulations, it's very difficult to run complex experiments of how an entity behaves in a series of situations, with the only changing variable being the entity's initial beliefs.
I think that underscores the crucial difference about doing simulations in this context: You're simulating a being that can itself do simulations, and this is the defining aspect of that being's cognitive architecture.
What must a sane person1 think regarding religion? The naive first approximation is "religion is crap". But let's consider the following:
Humans are imperfectly rational creatures. Our faults include not being psychologically able to maximally operate according to our values. We can e.g. suffer from burn-out if we try to push ourselves too hard.
It is thus important for us to consider, what psychological habits and choices contribute to our being able to work as diligently for our values as we want to (while being mentally healthy). It is a theoretical possibility, a hypothesis that could be experimentally studied, that the optimal2 psychological choices include embracing some form of Faith, i.e. beliefs not resting on logical proof or material evidence.
In other words, it could be that our values mean that Occam's Razor should be rejected (in some cases), since embracing Occam's Razor might mean that we miss out on opportunities to manipulate ourselves psychologically into being more what we want to be.
To a person aware of The Simulation Argument, the above suggests interesting corollaries:
1: Actually, what I've written here assumes we are talking about humans. Persons-in-general may be psychologically different, and theoretically capable of perfect rationality.
2: At least for some individuals, not necessarily all.