The Royal Rumble may have been the first time he was actively booed to such a degree, but it is not the sole reason behind the hate. Like Stroud said, it started long before that. I thought I would type this out to remind everyone just how long this has been brewing (forgive me if I get some things out of order).
The Shield breaks up. Dean goes into a hot feud with Rollins while Roman goes into a cold feud with Randy Orton. Roman wins, nobody cares because it's sandwiched between Nikki Bella's heel turn (yes, people cared more about this) and Brock squashing Cena.
Roman gets hurt. Dean gets extremely ****ing over during that same Rollins feud. Roman, meanwhile, is made to cut ****** satellite promos in what is the real first step of his downfall. WWE feels as though they have to remind us on a weekly basis that Roman Reigns still exist, even though absolutely no one forgot.
It is also heavily rumored that Roman Reigns is planned to go over Brock Lesnar at WrestleMania 31.
Next, Dolph Ziggler gets the spot Roman probably was supposed to get at Survivor Series, and also gets mega ****ing over for it. This is while Reigns is still cutting the terrible satellite promos.
The Punk podcast happens. This is not the sole cause, as some people have claimed, but it does draw more attention to WWE's Reigns agenda.
Roman Reigns wins Superstar of the Year. Some people think it's legit, some don't. What I think most people agree on is that it was completely undeserved given the other people on the list, and even if it WAS legit, it still came off as WWE forcing it within the context of the other stuff. Perception is reality.
Reigns is then inserted into NXT Takeover: R Evolution, and he says that he's going to be the first NXT Alumnus to win the WWE World Heavyweight Championship. Everyone's like, "WTF, he wasn't even there that long."
He comes back at TLC. The return itself is pretty hot, and then he completely ****s up the promo afterwards, mispronouncing a simple word like declare and then standing there like a goofus.
Daniel Bryan comes back and inserts himself into the Royal Rumble. Everyone goes nuts, thinking there's hope after HAVING PREVIOUSLY THOUGHT that Reigns was a lock to win.
Reigns cuts the sufferin' succotash promo, and then the Jack and the Beanstalk promo. Everyone assumes that there's no way he could be getting the big push if he's cutting promos this bad. Cue that familiar Edge video.
WWE books the absolute worst Royal Rumble match in history, making the previous year's look like a delicious piece of cake in comparison. They take that hot Ambrose push and say **** you. They take the rise of Dolph Ziggler and say **** you. And yes, most importantly, they take the return of Daniel Bryan, and possibly one of the best stories we could have ever had, and say **** you.
Then they bring in the ****ing Rock to try and force us to cheer the guy. And because the rest of this **** has been so ridiculous, THE ROCK GETS BOOED.
In the weeks that follow, they attempt to make Bryan look like the bad guy who is attempting to steal Reigns' spot, and then have Reigns beat him. Bryan endorses him and the people who have paid enough attention to this entire thing are not buying it.
WrestleMania now features the three stars of the fall in a nice, big ladder match while the Chosen One gets to headline WrestleMania, after WWE has done an absolutely, astonishingly, outrageously bad job of building him up. And they are so cowardly and insecure at the idea of Reigns not being over that they are not going to have him face off with Lesnar until the very last week.
Also, the story has become more about Lesnar with him basically serving as Punk 2011, circa 2015, which I'm sure is not going to help the WrestleMania reaction for Reigns.
There's the full, complete, and correct narrative on how this came to be.
