Depending on where you are in the world, certain types of weapons and armors may not be allowed inside a city. And in other places, would compound any legal trouble you get into. Guards will react suspiciously to heavily armored visitors. That sort of thing.

I realized that afterwards.  At first glance the Jack armor appeared to have the same cost as the full suit.  I looked again, and it wasn't quite so, but it is close to it.