Since Dale Sr. was killed, there have been several game changing improvements in car/driver safety:
SAFER barrier (resilient crash wall)
HANS device (head support that prevents the brain stem from disconnecting from the spinal nerve bundle - this is what killed Adam Petty, Kenny Irwin, Earnhardt Sr, Tony Roper and several others)
COT chassis - a standardized chassis with crash crumple zones and more robust roll cage and seat system.
They have achieved a fantastic safety record since these were adopted.
The developments you listed are all well and good. But this restrictor plate racing is just another disaster waiting to happen. And NASCAR won't change it until someone else gets killed.
I look at it this way: In the old days, after a crash, the car survived for the most part but the driver was killed. Now, the car disintegrates into a pile of rubble from which a dazed driver emerges relatively unhurt.
Generally speaking.
Safer and Hans... Great.
COT stinks on ice...
So does green fuel, restrictor plates, and only having half the season available for those of us without cable tv.