Having a criminal act dealt with by police outside the Armed Forces would provide greater confidentiality. When you file a complaint in the military, everyone ends up knowing. It goes up the chain of command to the commander at the top, then it comes back down again. All your colleagues are aware, then you are judged, fingers are pointed at you and the unsavoury comments start coming. In addition, the attacker or the bully often has a higher rank, so you have not a lot of power. If you are not very important in a regiment, you are more easily sacrificed. The Army wants to keep those with most experience and they are the ones committing the misconduct.
In terms of confidentiality, having criminal acts investigated outside the Armed Forces would give the victims some protection. It's critical.