Dude can look slick when he wants to. Reigns has the look of an Evolution member (a Batista), but Rollins is more an Orton which I guess they were looking for. The young, good looking workhorse that'll be molded into a diamond. Plus this kinda sets up Rollins as the Orton to Reigns' Cena. The rival. Rollins and Reigns were the bromance within the Shield so him turning on Reigns creates an instant blood feud. To quote Roman himself "Trust is dead to me".
Plus Hunter has been high on Rollins since he was signed so I guess it makes sense that he wants to mentor him more up close alongside Roman.