I see what you're saying petru. A lot of folks feel that way about a lot of items - the US doesn't, but other nations actually have rights that travel with artwork, for example. For example, an artist might retain "moral rights" in his art to prevent its abuse.
I mention that to show there is a good deal of support for what you're getting at. I think it's complicated, and especially with mass-produced, hopefully-identical-to-spec industrial products, it becomes even more complicated. But that's a tangent we don't necessarily need to chase.
I mostly just wanted to remind that one man's garbage is another's gold. I don't think it's bad to joke about things that are silly (I think most agree that rifle's silly), but a lot of things look silly to a lot of people. I'm just personally hesitant to ever outright condemn a particular modification, accessory, weapon, etc. on the basis that you've now just suggested a restriction on firearms - and we all know where that goes. It's unfortunate, I agree, but posterity has to pay part of freedom's price.