The way I handled the mechanical imbalance of OCCs/RCCs was by using RW tactics.
If the NPCs see a Glitterboy and a few Atlantean Tattooed Men charging them, unless they recognize the Atlanteans for what they are, they will concentrate fire on the obvious threat- the Glitterboy.
Its like a modern army seeing a main battle tank surrounded by infantry. Sure, the infantry matters, but the obvious and immediate threat is the tank.
In the meantime, the "lesser" threats have a momentary reprieve from being targeted by NPC railguns, etc., right up until they prove themselves to be a danger to the NPCs or the Glitterboy goes down.
Now, why exactly do you want that built into character creation?
Because its realistic(ish):
In a given military or quasi military organization, no two units have the same strengths and weaknesses. The tank is powerful, yes, but without support from other units, it can be destroyed with alarming ease...by 2 lowly infantrymen hiding in the bushes with a LAW.
The imbalance in OCCs/RCCs reflects this.
Because it promotes roleplay:
If you're in the middle of a MDC battle without MDC armor, you've brought the proverbial knife to the proverbial gun fight. Your PC can't just stand there and fight to the bitter (and quick) end- he has to think & act like someone who is a bit fragile for the events of the moment and find other ways to contribute.
Because...well, its 4:30 AM where I am, I'm going to leave additional justifications to those that want to or need to add them.