The laws that are enforced are the ones that are remembered, I suppose. It could be a positive thing that no one remembers that, though it should not be in the books I agree. Perhaps our legal systems have become too bloated with age and should be prescribed a diet and exercise regimen? xD
I recall hearing about a system for that in some country a long time ago, where all laws would be read out annually and if one was ommited and noone pointed that out, it'd be removed from the books are unnecessary. Something like that should probably be in place in modern lawmaking. For example, if the law was not invoked for a certain period of time, the senate would be required to vote whether to keep it or not. That'd get rid of most of those silly, outdated laws that litter the legal system.