Believe it or not, there are other ways to capitalize on someone's popularity, besides throwing a title on them. Punk's position on the card isn't all that bad. He's still top-tier, majorly popular babyface, he just isn't given the title. They have to establish Daniel Bryan first.
While they spend the time building Bryan, they can keep Punk busy with the stuff with Heyman. By the time the Royal Rumble roll around, I think people will clamor at the thought of Punk getting his run with the belt. It will feel overdue. And that's the point. That way, his eventual title victory is gonna be so god damn satisfying to the fans because it's delayed. There's money to be made in the hold-off, as well.
Yes, Punk is popular. But, they could still derail his path with a few things along the way. If they hold off, instead of hotshotting him to the title, I bet the response will be amazing.
Putting Punk back in the main event without actually putting the title on him does give the main event scene a boost. But this would be a half-ass attempt at best. It's just not the best scenario, in my opinion.
I understand the Raw roster doesn't have as much depth as some would like, but Punk could really serve to elevate Ryback during this time. If Ryback is going to be made to look like a beast, then he needs a substantial heat magnet like Heyman to latch onto, and majorly popular babyface like Punk to oppose.
Besides, if they just toss another WWE Title his way too soon, it'll lack that monumental feel. Punk has spent the better part of last year in the title mix.
At this point, while his act as a babyface is still fairly fresh, he could really lend a hand in elevating other talent like Ryback. The belt isn't needed on him just yet.