There is more to laws than a binary “legal or not” determination. They also include how a crime is to be punished. That part of a law is much more sensitive to shifting cultural standards.
Take for example the discussions regarding murdering in self-defense. It used be treated like any other murder, but we realized that it was unfair to would-be victims. That’s how we got “stand your ground” laws. However now people are criticizing these laws for encouraging murder and paranoia, a significantly unintended consequence. There been difficulty addressing “stand your ground” because they are entrenched into case law.
A sunset clause would give easier access to the people for reassessment of “stand your ground.”