No, it shouldn't. Heavy armor straight-up stopping bullets would be gamebreaking. TTK is already too high compared to Insurgency. Being "super-effective" (which I assume to mean stopping 4+ shots) would make it a higher TTK than Call of Duty and other similar modern military shooters. At that point, it would be closer to TF2, Overwatch, Dirty Bomb, etc. than Insurgency.
While I don't agree with what OP's saying exactly, I do think Heavy Armor should at least do something in-game, because right now it really doesn't do jack shit. Helps against battle rifles, some handguns, and some SMGs, but it makes literally no difference against any assault rifle, shotgun, or LMG.