Taker got cheers even when he did the whole ministry thing. He was clearly heel and although he got some boos from (say) the casket match with the Rock, people still generally loved him. Now don't get me wrong I don't intend to even compare Cena to the Undertaker, but I just mean to give an example on how the crowd will even cheer on a heel.
As for everything else that you said, I don't necessarily hate Cena. Hate is pretty strong for me to use, but I also do not like Cena all that much. I think it would be interesting for Cena to make a turn to Heel for a while like Hogan did with the NWO. Hogan's abrupt change to a villain devastated his fans, but it was further character development. Like I said before I think Cena WANTS to change things up, but outside politics play into it in more ways than one. Cena is the face of the WWE whether we like it or not as long as the kids love him and it will also reflect positively on Linda McMahon's part in Senate.
It doesn't mean he was a successful heel. Heels should get mix reaction and mostly heat. I dont hate Cena the person, I hate the fact that he's over pushed and gets credit for everything. Him being a heel, makes it even more worst he will still be pushed to the moon. I don't like the way how Cena is everything in WWE, things should get back on truck when things were about more than one guy, back in the time it was about 5 or 6 guys being in the same position and getting the same booking and advertising. Cena gets the best booking, the most advertising, and the most hype or push. I don't hate him because he's a face it doent matter to me as long as everyone gets the same treatment and recognition. So it hurts because if Cena leaves the WWE, people will say that WWE is dead, and many say "Cena is WWE" so is that safe for the comapny. I think Cena is selfish and egotistical for not trying to put a talent over or trying to change WWE, it makes more sense than Punk doing it because he has the most power. There is so many guys that deserves the same treatment why there isn't 5 or 6 guys in the same position.