Pretty much this. A lot of fans no longer care to suspend disbelief to the point of viewing most heels as "evil" and that's a reflection of society to some degree. Bray Wyatt is a vicious, hypocritical madman with delusions of godhood who wants to "burn the old world down." He's not exactly the type of guy that people 25 years ago would cheer for. John Cena, on the other hand, is the ultimate good guy/hero who stands for purity, moral truth, etc. However, people don't cheer for Cena the way they did even 8 or 9 years ago.
Because WWE wanted fans to boo Bray Wyatt, and by WWE I mean Vince McMahon, many fans decide to do the opposite in what comes off, at least to me, as some piss poor attempt at rebelling against authority, "the machine" or "the man" if you will. Sometimes, it strikes me as kinda pitiful really because some of these fans genuinely think they're making some sort of cool, edgy statement about themselves. It goes back to the unwillingness to suspend disbelief or to view things in a more traditional manner that's prevalent in society today. For instance, when I watched The Dark Knight in the theater years back, some people would start cheering or applauding when Heath Ledger as The Joker would start on one of his psychotic rants or brutally slay somebody while booing whenever Christian Bale as Batman would start to verbally chastize The Joker about morality and people's goodness.
If you don't at least try to suspend disbelief in regards to some aspects of pro wrestling, or even the movies, you find yourself enjoying it less and less as time goes by. That often results in people devolving from smarks into trolls who watch or post about them for little other reason than to voice their hate of it.