It's probably the best underdog story WWE ever told, and they did it completely begrudgingly.
WWE would like you to think that they listened to the fans and deliberately crafted a story where Daniel Bryan rode a wave of momentum in 2013, and with the help of the Yes Movement, overcame WWE management and main-evented WrestleMania XXX in a completely organic fashion.
In reality, WWE had no plans for Bryan to main-event, and basically gave zero craps about the Yes chants. However, after the Royal Rumble, when CM Punk walked out of the company discouraged about not main-eventing WrestleMania, WWE had to re-arrange the whole show. When they realized that Batista was not going to work as a babyface against Randy Orton, they decided to insert Bryan in the main event. It killed two birds with one stone: it saved the show, and it was a good way to spite Punk by giving his coveted main event to his personal and professional rival.
Of course, whatever cynical backstage chicanery there was, sometimes, fiction is more important than reality. The story of Daniel Bryan overcoming the odds and closing WrestleMania as WWE Champion is one that will be in WrestleMania video packages forever.