Why do so many dislike him?
He's blamed by many for the introduction of the PG era but instead of trying to lash out at the haters, he's accepted full responsibility of being the face of an era. He deserves even more credit for fronting this massive transitional period even though he may not have even initially agreed with the direction of the company.
Let's also dispel the narrative that he hogs the spotlight. He doesn't control the show, he doesn't write the storylines, he doesn't decide whether he's in the main event or not, the money does. He draws the most so he headlines the most, it's not rocket science. It's not his fault that the WWE didn't build enough stars off of him for several years, Vince had tunnel vision and saw it as the Cena show. And when a company doesn't create enough top stars, one man will be perceived to be 'shoved down throats,' in the attitude era there were a plethora of top guys. So, of course, one main draw at the top was always going to draw resentment from the masses.
At the end of the day John Cena has given his life to our beloved company and taken it to new heights, whether you love him or hate him, you simply cannot ignore the impact of John Cena.
He will forever be the standard bearer of this century.