You have to be really good to win more than one world title, he is obviously very popular with everyone in the sport, a really nice person but I wouldn't go out of my way to watch him race.
His longevity is based on playing it safe. If every rider rode the same way as Greg Hancock the sport would be boring. If he misses the gate then he 99% settles for where he sits in the race.
This post will get criticism from Greg's die hard fans but its just my opinion. If we had 15 Greg's in the GP there would be nothing to talk about. We will miss Nicki and Gollob more than we'll miss Greg when they are all retired.