#3 The current babyfaces suck
When your current product isn't as good as your old one, of course, the fans are going to crave for the old product. If you look at Raw today, you'll be hard pressed to find a main event babyface that anybody cares about at the moment. Roman Reigns is dull, repetitive and not charismatic, while Seth Rollins is not firing on all cylinders, yet.
Fans chant the straight-edge wrestler's name because they desire his entertaining presence and detest the boring stuff they have to endure right now. In every era, fans need a top star that captivates the masses, with Cena on his way to Hollywood; the WWE Universe don't have this at the moment.
So they chant for the one who could bring back edginess to the show.