As I said, pandering is part of Cena's job as a face, every face do that.
Punk really received strong push, I don't know what Vince can do for him besides shooting to the company and breaking kayfabe must of the times.
Punk outsold Cena in merch only once, he couldn't continue to do that, plus, he never was draw. I'm not saying he's failure because apparently he's not, but he certainly is over-pushed, he may be entertaining for you, but not for me nor the other audiences who tune out every time he appears.
I can think of plenty who were pushed harder than he was, though I think the problem with Punk's push isn't really punk himself but rather the direction he was pushed in. The quality of the booking I think might to be to blame, but again only started watching for the last year or so, so my opinion probably lacks the same perspective as yours or anyone elses. Everyone has their own taste, their own preferred flavor, and while I do prefer CM Punk personally over John Cena, personally I'm a bigger Ryback fan personally, but I like a variety so WWE works in some ways.
With John Cena's injury, maybe this is a good time to build up CM Punk's stock without the worry of being overshadowed. I know other faces have 'pandered' but in a way they all had a well defined and captivating character. The Rock was larger than life, rediculous but charismatic, Stone Cold was a alcoholic anti-hero who was ready to kick anyones ass, Hulk Hogan was the ultimate patriotic figure, practically the Captain America of wrestling (Minus his stint as Hollywood Hogan), and then you have John Cena, who only really gets cheers when he sucks up to the crowd, which feels more like a crutch than the typical face of the company deal.
Then again, this is all opinion, it's not that I believe that John Cena shouldn't appear on television - that wouldn't work. I just feel he doesn't need to main event every time, people will pay to see him in a solid match, cut a promo, the works. I personally would pay to see a world champ main event legitimately regardless of whether or not he was fighting Cena.
It just feels like an over saturation of John Cena is impairing the business, I like to compare WWE to majort comic publishers like Marvel or DC who tend to oversaturate the market with iconic characters when they are unable to really do anything else with the rest of their thousands of characters. While some characters really have no hope of redemption (same goes with wrestling gimmicks and wrestlers themselves), other times writing proves sufficiently capable of moulding a good fanbase around re-established or new characters.
While bad writing can sufficiently kill them.
OF course, different mediums, different companies, but each rely on a good deal of writing and a good deal of sensationalism. The difference is Wrestling is more reliant on the individuals themselves to play the characters and perform the moves.
Wow, I really rambled on there, my apologies.