I get why guys resent Rock. Maybe its not justified but I get it.
I think we all have a relative that does better than us. Your parents, grand parents and your aunts and uncles rub it in your face. He then shows up on the odd Thanksgiving. Marching in like the conquering hero. He makes small talk, condescends to you about spending more time together, but you know he has no intention of staying in touch. One year you would like to knock him off his throne and show him he is no better than anybody else.
Personally I think that is Cena's motivation in the feud and my guess is how the other guys feel in reality. Its not necessarily justified, but it is understandable.