Historically speaking, if the fans are 'into' a superstar enough, they'll usually eat up almost anything that person does in the ring, even if it's mostly just basic punches and kicks. See Batista for reference. Or Stone Cold for that matter. It seems to me almost every one of Reigns' matches since The Shield ended have gotten a ton of positive reception from the crowd.
And to be fair, is Daniel Bryan's basic move-set in WWE any better or more extensive than Reigns'? I know Bryan has a whole long list of moves and submission maneuvers in his repertoire that we don't ever get to see on display (although for all we know, the same might be true of Reigns, too, albeit to a considerable less extent), but if you look at the signature ones that he uses in every match, his skill-set isn't all that more varied than Reigns'.
Yep. They could definitely book him to outsmart and defeat Brock Lesnar, and make it believable.
However, I would have just had Seth Rollins cash in on him afterwards. That's been a desire of mine going back to at least last Fall... that whoever was standing victorious with the WWE Championship at Wrestlemania (a babyface, of course), Rollins would swoop in and take their big moment from them by cashing in the briefcase. It just makes too much sense not to, no? Rollins would become the first man to cash in at a Wrestlemania, and the fact that it would happen exactly ten years after the inaugural MITB match at WM21 would make for a cool little footnote.
I agree that out of the things 'wrong' with Reigns' push, his kayfabe booking is hardly one of them. According to data that I collected elsewhere, Reigns has obtained clean victories over ten different superstars in singles matches throughout his entire WWE career so far (in no order): CM Punk, Big Show, Luke Harper, Kane, Randy Orton, The Miz, Mark Henry, Fandango, Seth Rollins, and ADR. And to be fair, seven out of ten of these folks are former world champions. That's more than the likes of Goldberg and Batista could say they beat prior to receiving their big pushes back in the day.
Who did Goldberg beat before winning the championship from Hogan? Other than a couple of prominent midcarders (like Raven for the US Championship), the only type of people he defeated were lower-carders like Alex Wright, Hugh Morrus, Disco Inferno, etc. Sting, Randy Savage, Ric Flair, Lex Luger, Roddy Piper, The Giant, DDP, etc... it's not like he beat all or even any of these individuals before taking on Hogan.
Who did Batista beat? Jericho at Vengeance 2004 and Chris Benoit a couple of times on Raw in January of 2005 were it.