The problem with brain simulators is that people who write them are typically neuroscientists, who are not interested in building AI. They just want their simulation to produce similar neuron behaviors to what their sensors record. Their simulations are at such a low level that even if the results produced by the simulation are identical to the real signals, it's just as hard to understand what's going on on the higher level as when looking at the real signals.

Also, those low level simulations are so computationally intensive, that you can forget about simulating any interesting high-level behavior in a reasonable time frame. Moreover, many of the simulated low level details might not be relevant or necessary for intelligence.

People in AI would benefit from a good theory of how brain works, unfortunately, initiatives like Blue Brain Project have not produced such a theory (at least not yet).