People are allowed to customize the look of the guns. I haven't ever heard of any gun or people being shamed for buying guns because of how they like them to look.
In another perspective, making cars faster, boosting, lifting/lowering, and modifying them make them deadlier, too. They do affect the performance though whereas the look of a gun does not.
I think the most they can do is modify the magazine count, trigger pressure, and maybe bump fire? But bump fire reduces accuracy.
I'm a gun owner but not really into spending money on how they look. Most of my collection is hand-me-downs or family heirlooms. Won't knock someone for getting what they find aesthetically pleasing.
Ah shit. You've got a legal point.