If your plan is to get shot and have your body armor absorb it, you need a better plan.
I agree that's a horrible plan but on the other hand I don't plan on going in the water when I'm canoeing but I still wear a floatation vest.
The same could be said for wearing a gas mask around town as well. I think the "likely benefit" vs. the cost, weight and hassle of both these items lean towards leaving them out of your daily wardrobe or even your bug out kit. But that's just my opinion. I'm sure I carry lots of stuff that some would scratch their heads in wonder about.