In my life time, that curve has been redesigned in a major way...three times. It used to be almost on level with the ocean and waves came over it (and eroded it). So they spent millions in the 70s to raise the road. But still there were accidents (people actually go flying off that curve into the Pacific Ocean, despite the warning signs, speed limit drops - and a major widening of the road).
In the 90's until the 2010s, they made the curve less sharp, poured some concrete, widened the entire stretch of road and put in guardrails to make it plain that one was going to leave the road altogether if they didn't mind their speed. Tons more stop lights (but not in that section, because...there are no cross roads or any reason to stop). It's a highway.
Should they ban bikes and pedestrians altogether? I don't know, but last time we were there for a family dinner (on a weekend), I was shocked at how people were parked all up and down PCH, and the pedestrians instead of taking the inner route (narrow path between hedges/fence and parked cars, pedestrians were walking right on the edge of the highway - much much easier to walk there, of course, but so scary with cars going by at 60 mph or more (speed limit is 55).
I think it's already prohibited to walk on the actual highway, but people do it all the time (so yes, it would have be more enforcement - that area doesn't really have its own police station or CHP, it's operating out of West Valley, IIRC - so maybe a couple of squad cars?). There are not many businesses right there to tax, either.
It's very alarming to see the statistics on this, after this terrible tragedy (I sometimes commute past that same spot but haven't been able to bring myself to go that way since it happened).
So very sad.