Part of the reason why fans latched onto Daniel Bryan so much is because of how sick they were of John Cena as a living super hero. Bryan is presented as more of a regular guy, one who had to work his way up to the top after being held down for so long. It's the same reason that CM Punk exploded in popularity: he represented a "real" wrestler, someone that didn't fit in with pre-conceived plans of what a wrestler should look like. More so than anything, it was talent that brought them to the big time. A lot of people can relate to Punk and Bryan, and how they had to fight for everything they earned. As much as Cena wont admit it, he basically has the exact look that Vince goes for in a top star, which is why he got the opportunity that few others have. When Cena does call it a career, fans don't want someone just like him to take over. Ten years of the same thing is way too much as it is. Adding on a few more could be lethal. The audience doesn't want another good looking, dominant jock with a limited amount of wrestling moves as the face of the company. Sadly that kind of sums up Roman Reigns.