This is supposed to be his "Swat mode"
Robocop 1.0: looks like the original suit, but is turned down, because in the script, a test study with criminals make fun of it and say it looks silly. They even sarcastically reference Eddie Yang(the guy who designed Iron Man in the movies).
Robocop 2.0: Looks similar to the 1.0 variation with minor tweeks, but his armor is tinted green.
Robocop 3.0: Is still similar to the others, but his armor is now black, and has a big OCP sign on its back.
Robocop 4.0: This suit can now change colors. It has a civilian mode that makes him look like a cop in a blue uniform. When he sense danger, he'll go into "intimidation mode", and his suit changes colors to all black and looks like a SWAT uniform.
Having an "intimidation mode" makes some kind of sense, I guess, but all the other stuff just seems so unnecessary. Is there any reason we really NEED to see him in a bunch of different armors and colors over the course of the film?
What the heck does that have to do with character or story?
How do his different modes detract from character or story?
Besides, he's part machine. It's logical to make tweaks and upgrades as he is tested in "real life" situations.