Pro: Safer racing.
While racing will never be 100 percent safe no matter how many soft walls or in car devices they create, its pretty safe to say that the increased stakes of the new playoff system make drivers a little more willing to act dangerously if it means winning the Cup at the end of the year. Unfortunately for NASCAR, the drivers and the fans sometimes, it can have disastrous results.
Take the 2015 Cup Series race at Talladega Superspeedway for example where Kevin Harvick knew that he had an engine going down, but decided to chance staying on the track in order to keep his spot in the next round of the playoffs. While Harvick did ultimately end up gaining a final spot in the next round when all was said and done, it only happened after a huge wreck took out many contenders in the race and jeopardized their safety.
In the end, not having the playoff format would encourage drivers to be less dangerous with their decisions and it really could go a long way in protecting many of the drivers on the track at the end of the day. Of course there were times where dangerous accident happened during the previous versions of the playoff format, but one could argue that they happened less frequently then before.