Need and deserve shouldn't mean anything in professional wrestling. If you only give attention to those who work hard and aren't drawing big money, your company suffers. It's never about deserve, nor should it be.
Also, as someone else already pointed out, how can you admit Rocky winning the title boosts buyrates but doesn't "the correct way" for WWE to go? That doesn't make any sense.
It's nothing like Brock Lesnar beating The Undertaker. CM Punk is a heel who has cheated (most of) his way to this 400+ day reign. A big name babyface, part-time or not, should end it. Brock Lesnar, a heel, ending Taker's streak would be terrible. Then again, anyone ending Taker's streak while he still has gas in the tank would be terrible. Taker's a draw at Mania. There's the difference.
Rocky shouldn't be blamed for the current roster's inability to get themselves as over as he once did. Just because this current crop of talent doesn't compare to Rocky or other top guys of the past doesn't mean you drop what makes you money in hoping they will eventually become draws. Bad for business. Rocky's not depleting the starpower of these guys. The blame lies with WWE and those wrestlers.
The problem with this theory is having confidence in lower card guys. They aren't getting over, and haven't been long before Rocky came back. WWE is bring these guys in to draw money because the current crop doesn't do that. They're not bring him or Brock in to build new stars, because the guys the IWC champions for have no potential of ever making it big anyhow. They aren't there to put young guys over. They're back to make the company (and themselves) some cash.
You're definitely wrong. There's no one on the roster outside of John Cena and Ryback (maybe Orton) worth giving that push. Who has that kind of potential? No one, from where I'm sitting.
On the Taker point firstly, I have to disagree. It's practically criminal for Taker to hold on to that streak till he "has no more gas in the tank". If he has one more great Mania match in him it absolutely should be used to elevate someone, be it Punk or Ryback or my pick Wade Barrett, someone young should be put over in the same way Taker was at the beginning by Jake Roberts, Jimmy Snuka and Hulk Hogan, there is no excuse for that not to happen and blaming the talent for not getting over in the same way is ludicrous, because Taker got where he is cos top guys put him over right at the start to build that aura, same for the Rock and Triple H. That there's any question of them doing the same or having a say "who is worthy" of that honor is insulting to the roster and those who put them over and stinks a bit of Bruno Sammartino's bad attitude. Jimmy Snuka never said "Nah, not putting that kid over at Mania, it's a stupid gimmick and I don't think it'll work".
As for the Rock, there is an element of staleness to him, but that's mainly because he trancended being a wrestling character and became a legit Hollywood phenom. Make no mistake he is in the top 10 actors in Hollywood and seemingly the go to guy for new franchises right now. that he still wrestles is actually the coolest thing about the character, for all the critisism he took for his "never going away again" comments, in reality he hasn't... He only does a part time schedule but this will be his 3rd Mania in a row that he has appeared. That being said he can't veer too drastically back to WWE or producers will start to think of him as a wrestler first again, right when he has finally got Hollywood's respect.
How could he change it up? I think he could come up with a new catchphrase, we saw how quick "Boots 2 Asses" took off or when he was doing little video clips like "Shrivelled up monkey penis". Punk was kinda right in his promo in that nothing new has passed his lips in a while so a new quip would certainly help.
Also I think he could do with new attire... the short tops and tracksuit bottoms look is a little 2004. Jericho changes his look everytime he comes back and it is a big part of why he can do that. I can remember when The Rock was the trendsetter for attire, when he wrestled in a 500 bucks Silk Shirt against Foley. He is a Hollywood A-Lister so why not dress the part or even borrow a little from the Rick Rude playbook and maybe get some custom tights/jackets for each opponent, after all at 10m a movie he can afford it.
He could also get a new move... In today's WWE the People's Elbow looks more dated and fake than ever, keep it as a spot, even keep the Rock Bottom but nearly every veteran superstar who has had time away has added at least one new move to their finishers, Jericho added the Codebreaker, Taker the Hells Gate and Lesnar the Kimura. For Rock I think something a bit "old school" could benefit him. Maybe use the ropes as a kink into the Rock Bottom so it's more of a slingshot move or an old fashioned Samoan Drop from the top. Something to show that while he is an Actor, he hasn't stopped learning his craft as a wrestler, that alone would silence a lot of the critics who think he is living on past glory.