Because there’s no reason to, especially something like an ancient law that was technically invalidated by a Supreme Court case. There are invalid laws on the books basically everywhere, lots of states and many more counties and municipalities, because there’s no real benefit to legislatively repealing or rewriting a law that’s been invalidated by a court, except to make less (billable) work for lawyers. Since most legislators are also lawyers, why would they put in extra work themselves that serves no purpose but to make it harder for their colleagues to earn a living?