I think it has a lot more to do with where you drive, not when the truck was built. I had a 2001 Tacoma before I got my 2005, the '01 also had a lot of paint chips.
I live in WV and they use cinders on the road in the winter and by the time spring rolls around the cinders are everywhere. That and the fact that I run the Dueler A/T tires which seem to pick up gravels and rocks more than the factory tires.
Just my two cents worth.
