I don't think the answer lies in ALL or NONE approach

If a bridge is so old or built so poorly that it can't support the weight there can be limitations made, creative solutions employed.

Some locations may view it as a tourism incentive, a benign act or an artistic display (many do go see these displays... heck photographers are constantly taking pictures of them)

Again some bridges or fences can't handle it and some can. We can figure it out ... to just toss the baby out with the bathwater is not the solution.

P.s. it's kinda funny that we're worrying about something as benign as this. Engineers can figure out what the bridge can handle and then those in charge can make policies. We're not engineers we are prone to just make up facts that suit our cause... let's let people who know stuff figure things out. I know some bridges just get someone to cut the locks off every so often. The lock sales are actual business, the metal recycling incentive is probably decent if they really are as heavy as people say.

And if a local government official is too lazy and just wants to BAN them outright, just because they have a personal issue, I say they should be fired or removed from office. There should be solid verifiable reasons in a case by case scenario.