You can't fix the most evident issue of IAAs - lack of time. Most rounds last less than 2h 30min. A complaint filed in before 30 minutes into the shift is basically completely unheard of. More often than not, these happen after the first hour. That would leave you with a reasonable amount of time, but "the shift is over" mentality grows as we approach 2h mark.
You are effectively left with 30-45 minutes before all investigations and decisions are overruled by "the shift is over".
It's enough to interview one, maybe two people, provided they are willing. However, if the issue is larger and you have an appropriately larger group to investigate, you are forced to do your job half-assedly. You don't have time to confront all points of view with each other, so you just end up taking a bunch of guesses on who is wrong or lied, which isn't particularly impartial and plainly against your job description.
My point is: IAAs would work much better if the rounds were longer. It's unreasonable to change it just for IAAs, so it will stay like this.
Regarding "obstructing an investigation", I'm afraid it would lead to further corruption of both IA and Security.
Firstly, Security doesn't care about IAAs reporting crimes. I have been repeatedly assaulted as one and Security always ignored me. Once I even brought a body scan proving someone tried to stab my eyes out with a fork. They weren't even set to arrest.
Secondly, if it applies to Security Officers, we will see people enforcing police state. "Let me in, I'm investigating. No, you can't know what or why. Just do it. You won't do it? Fine, then you're under arrest." It's assault of an officer, but far easier to abuse.
That being said, perhaps we are (or is it just me?) a bit too afraid of giving IAAs some power.
Maybe, rather than being abused by bored players, it will attract those who want to put said power to good use?
And regarding moving them under NT Rep, I would say no. There's already a lot of positive energy between IAAs and Reps, which I've experienced from both sides. They can make an awesome team without making it official.
So why not? Because, frankly speaking, Magistrate needs IAAs more. I know I've just said IAAs usually don't have enough time to investigate, but they are still doing a stellar job in comparison to Security Officers or your average Detective when it comes to proving guilt or innocence.
Call me crazy, but as a Magistrate, I rely on IAAs. They can be foolish, overzealous, incompetent and all imaginable flavours. However, the most common thing is being bored and when you address it, they honestly try. I feel like Magistrate does much better job at finding tasks for IAAs than NT Rep ever will.