right, but why is that?
he's good enough to win the title, but not good enough to HOLD the title?
Sting's whole character makes him a better contender than champion. It doesn't matter which character either.
Surfer Sting had a perfect build up to his winning the belt from Flair with the inclusion in the Horsemen, then being turned on; the injury and then all the DQ victories as Flair kept cheating to save his belt...it all made the moment of his capturing the belt so epic.
Crow Sting was also given a great build up storyline as he chased Hogan and overcome the odds against The NWO.
Neither version of Sting was particularly well-suited to be a long-reigning world champ though because the chase was so ingrained in their pushes.
Plus WCW as a company (and even NWA before it) historically really didn't do the long-term face champ thing as well as they did the hell champ. That's why dudes like Flair and Harley Race would be champ for years while someone like Dusty Rhodes would only be champ briefly.