Yes great idea. Build a new rule into a nation-wide law just to solve a problem that needs no solving as "red light with static green right arrow" is a typical sight over here in Germany and drivers DO understand it.
It would be much better to change traffic la nation-wide so we can get rid of this ONE traffic light in Germany. Isn't it?
Changing the law and checking correct enforcement costs way more in people hours than the cost of operating a single traffic light. People underestimate the cost of regulation. Also, a consistent and simple set of rules should always be preferred and causes less human errors.