I've seen subtle changes over the years, and people have adapted or become accustomed to what they can and cannot accomplish. I've been to some tracks where people just raved about the incredible traction, whereas I noticed a number of cars having problems, prompting me to think, "So that's what passes for incredible traction these days..."
On a somewhat related note, I STILL see people leave the line trailing rocks, sand, and debris out of their rocker panels, dumping it right in front of their own slicks. Clean your wheel wells in the staging lanes, or do something to prevent debris from collecting there in the first place.