The points you say are important ones; however, there is no balance there, in my opinion.
The biggest complaint against what their system did is that they arrested the Security Guards on the mere word of the three who were last seen with Natalee, they let those three go and they did not have or borrow the forensic search capability that was crucial to finding the forensic truth in this case.
Add to that, they lacked the expertise and technical resources to seriously search for a body under the possibilities that she had been put into the ocean. After all this time, just about zero chance exists to find such a body, or if it were found, find crucial evidence on the body.
The Arubans have not only botched the investigation, but have also hindered it in some areas. Why O why have the Dutch marines not been helping to date? That is but one example.
I think this is the biggest factor. I think were it our LE, that soemone might have spoken with the security guards, but doubtful that they would have been arrested. Meanwhile, I do think the 3 guys would have been taken in for questioning and their car looked at, right off the bat.
I'm not sure just when they were first spoken to, though so it may have already been too late for evidence to have been apparent.