They started having him cut promos in an effort to let him show off a personality that he doesn't have.
Don't forget, he was OVER as the man of few words ass-kicker in the Shield. There was no reason to deviate from that because that's what he's good at. He's not a good talker, he's not very charismatic.
Keep it simple, stupid.
Oh, and of course, there's the fact that they were trying to force Reigns on people when they wanted DB.
But this is Vince's, "I turned(forced) a rapping John Cena into a fan-favorite regular guy" ego that thinks he can do the same for Reigns.
The reality is, everyone who boos Cena wishes he'd go back to his old character, or at least incorporate it occasionally.
Instead he went full cornball and never looked back....which is what they trying to do with Reigns



LIT
until this post. I like and hate the Superman Punch. It's just used too often and not even a finisher. 




it been a minute since he stomped on someones back and made em humble