To me not much.
It is true that we got better suspensions, helmets, boots, knee braces and so on than on Ricky Johnson's era, but at the same time the sport has grown so much technically that today any amateur kid at the track jumps, scrubs, goes faster and do things that most of the pros long time ago wouldn't even dream about.
A1 and Houston had some sections where it looked like BMX at 50 miles an hour. The one where Wilson got hurt and Roczen almost washed? Man, those guys are monsters.
The bikes are good. Riders and teams take it more and more professionally every year. Everyone, even amateurs take it seriously.
This made our sport to grow up a lot lately.
But safety did not. At least not at the same pace as the sport itself.
Neck braces came to save our backs and broke our collarbones. Chest protectors don't do much more than 30 years ago. Apart from boots, knee braces and helmets, what do we have to minimize the damage?