This.
Sometimes, people seem to act like he's some uncharismatic nobody that only got over because of a fluke WM fukk-up or something, when that absolutely isn't the case. Yes, he has the chant and the circumstances, but if the ability weren't there from the get go, he wouldn't have even gotten to that point. People forget that this guy has gotten over everywhere he's gone, and not merely because he's an all-time great worker. He can absolutely sell an angle as well.
On a larger note, though, the question shouldn't necessarily be "why is he popular," at least for us who follow the programs (if he were in a featured program, I believe that his popularity would be easier to explain to casual types. He isn't, so it's harder when he only comes out to look like a nobody in a program with 6 other nobodies). The question should be: "why was it THIS guy and that CM Punk guy that got SO popular with the fanbase?" It's an important question, one that I believe goes beyond mere wrestling tropes and gets into the realm of how wrestling plays off of, for lack of a better word, generational attitudes. The same play of generational attitudes that determined the massive popularity of guys like Gorgeous George, Bruno Sammartino, Hulk Hogan and Steve Austin.
The answer to that question would also explain why certain people, up to and including Vince McMahon, don't necessarily see guys like Bryan or Punk as their number one guy.
Just a thought.
and incorporating it to NXT.