"but the bikes and riders are also better so it evens out"
I don't understand this argument.
Are the riders magically not able to crash with a better bike? Obviously not, they are still crashing.
Crashes are nothing new. So why are they getting hurt in record numbers?
A popular quote (I think by RC) and I paraphrase, "Gravity hasn't changed".
Crashes are happening at ALOT FASTER speeds in supercross that ever before, on heavier bikes.
Force = Mass x Acceleration
Now think of the all multipliers you can add to that equation. They all make the end force go UP.
We want the force to go DOWN if we want less traumatic crashes. Lower speeds or use a softer racing surface to lower acceleration (deceleration), or lower the overall mass. There is no "better bike" in that equation (other than lighter bike).
Read the cycle news article. Carmichael comments that the nationals also have fast speeds, but the obstacles are not so close together so you have room to abort or recover. Other factors such as softer dirt and less jumping "up" are cited as equalizers for the high speed nationals.
Many people comment that injuries will happen. Villopoto's knee. Canards and Mo's freak collision. Things like that, but it's a fact we are seeing way more potentionally career ending injuries when the inevitable happens.
Sorry, I'll get off my soapbox now. I just don't understand why a large majority shrugs it off as "injuries happen in motocross, nothing we can do about it".