For example in the case of NXT the simulation could have been used to find out, how the forging works and how it distributes the fees. That was not done - at least nobody had written so. (Or was that too obvious, when that has been asked few times

)
Nxt works fine. The point of forging is not to be "fair" but to
secure the network -- that's what mining does for bitcoin too. The question is whether POI is secure. We won't know until it's studied and reviewed.
Totally agree that security is priority #1. We're testing a lot of attack vectors to make sure that someone can't just arbitrarily control their score.