The California approach seems more safe and effective potentially: have doctors annually determine a fighter's safe weight. Of course there will be a ton of debate as to how to determine that.
The idea of weighing fighters on fight day brings up the question: at what point on the day would they be weighed? I predict plenty of dudes will be missing weight on fight day, while others will be trying to rehydrate after their fight day weigh in. More hoops to jump through ain't gonna make for healthier weight cutting practices. And that's coming from someone who has cut weight before. The only thought in most competitors mind is how to win the fight, not what's most healthy. Some people unfortunately feel like it shows toughness to cut weight in unhealthy ways, so fight-day weigh ins just give them another chance to show how "badass" they are.