Explaining certain inexplicable booking decisions is ironically easy, with the most cynical of mindsets: Vince McMahon is absolutely mental, or least incredibly erratic, and is as set in his ways as your racist grandfather. He is a racist grandfather.
This bizarre mentality explains why, for example, McMahon refused to push the insanely popular Daniel Bryan ahead of WrestleMania XXX - and why, upon finally relenting to the pressure, he outright informed Bryan that Roman Reigns was The Guy going forward. Bryan = short, pale, scraggly. Reigns = tall, sculpted, handsome. You needed only a visual cue irrespective of how deafening the sentiment was. McMahon was deaf to it, and not without some justification, or at least explanation: the man has monopolised pro wrestling so thoroughly that certain Network television stations in North America are toying with the idea of purchasing the company's TV rights.
This, in turn, explains decisions more depressing than mystifying. John Cena dominated the Nexus because he sold metric f*cktonnes of merch; Randy Orton won the 2017 Royal Rumble because he was established and popular among the casual audience; Finn Bálor doesn't get to break the wheel because he is but a spoke in it.
These decisions...these are legitimately inexplicable...