In my opinion, these are examples of ultimately what's ruining wrestling, if anything is actually ruining wrestling.
What's changed are some of the fans, namely the smarks.
To hear people chant "you can't wrestle" to John Cena makes me shake my head at their stupidlity. I know John Cena isn't some sort of technical dynamo out there but he doesn't have to be. This is pro wrestling, not the Olympics. Cena makes tons of money for WWE, his matches are often quite good as are his feuds and he CONSTANTLY is able to keep fans interested in whatever he's involved in. That is what makes someone a true star in pro wrestling. I've said it before lots of times: if you're someone that can't make the fans invest their time in you enough to care about you, then it doesn't matter how good you look. It doesn't matter how handsome you are or how incredible your body looks. Doesn't matter what sort of athlete you are. Doesn't matter what technical skills you have. All of those things are great assets to have, but they come at a far distant second to making fans care about you one way or the other.
Cena is not constantly able to keep people interested. I didnt care about his Programs over the last 20 months with: R-Truth, John L, Big Show, Kane, Del Rio, Miz, -- Need I go on? And for the record I cared about Big show in the title pic, and I care about Kane now. Cena is no entertainment god. All these programs I didnt like were in the main event of a show that I do like. I like to finish the show to make sure I dont miss anything, so I watch. You make lemonade sometimes, doesnt mean you want it.
As for the fans ruining wrestling, I see where you are coming from but i must disagree again. Negative chants are meant to get under the performers skin, and the good performers like Cena actually encourage it. In fact "You can't wrestle" is just another in a long line of negative chants that the peformer may not have wanted, but encourage for showmanship.
Lance Storm - Fans didnt call him boring because they thought he was boring(even if they did). They did it because Stone Cold told them to.
Christian - CLB, he would cover his ears and jump up and down.
D-bry - Yes/No. Yeah they all hate him sure.
Kurt Angle - Fans knew Kurt Angle didn't suck, but the way he reacted to those chants was so perfect that even years later as a babyface they would tell him he sucked on the way to the ring
John Cena - Cena was rushed into the ME. It didnt show so much on SD against JBL. But once he came to RAW and was put into programs with people like Christian, Jericho and Kurt Angle, it showed that he couldnt wrestle, at least not like they could wrestle. And when the fans told him about it, his face would go flush red and he would look like he was going to cry and made the chant just as fun as the Kurt Angle you suck chant.
Wrestling encourages the audience to heckle, and most people who chant you cant wrestle at Cena these days know he can, and knows he can entertain.
But if you're trying to blame millions over the world for booing a guy who has been consistently booed for 7 years instead of just, I dunno.... blaming the company for not just making a babyface who people actually like? Then no, I can't understand where you're coming from.