That's actually where I live! And yes, tourists and people in general having sex in the dunes there is definitely a problem.
In any case yeah, I think all sex in public should be banned, including that. However I don't think it should be a rule that is all that enforced; if they are far away, isn't obvious and not bothering anyone, leave it be. Though maybe it should be better enforced at this particular location, going through the dunes could be a better experience if there weren't condms lying around.