NASCAR abandoned or reduced races at classic tracks like Rockingham, North Wilkesboro, Darlington, and Atlanta. And every track they built in the 90's was a superspeedway. It became the same thing week after week-draft, draft,draft. Pit strategy often wins those races. I think a lot of fans miss the smaller tracks that demanded a different kind of racing.
The playoff system was implemented when Jeff Gordon started to dominate the sport too much and have the Cup title all but wrapped up by Labor Day.
Which leads to the next issue. Gordon, who was from Indiana, not Tennessee or the Carolinas, was the perfect telegenic, smooth talking star for corporate America to hitch it's buggy to. Unlike the good ol boys you got the idea that he actually graduated from high school. But before you knew it, you had snobs like Tony Stewart, Kyle Busch, and Joey Lagano, who are nowhere near as friendly with the fans and media as your Petty's and Allison's and, for the most part, Earnhardt senior and Jimmie Johnson.