The difference between Eddie and Benoit compared to Bryan and Punk is physique and legitimacy. They had the better physiques, no matter how you slice it.
There are plenty of guys who've never failed a wellness test that look and stay in better shape than Bryan or Punk. And as far as legitimacy, they called Benoit a rabid wolverine from basically the moment he started being featured. He was an animal, a technical assassin, viscous, and destroyed guys before making them tap. Even with Eddie, he was a Guerrero, a warrior, a technical specialist who they always said had been in the ring since he was a toddler with legends instructing him, and then they added the lie, cheat, and steal. Benoit and Eddie had far more credibility in that ring as ass kickers than Punk or Bryan.
Punks a guy with a 400 day reign and a 6x world champ. The thing is who has punk actually beat convincingly? He's never beat Cena clean even as a face dropping pipe bombs. He got his ass handed to him along with all of the SES by Rey singlehandedly. Big Show handed him his ass. Taker squashed his ass in 8minutes in a hiac with entrances. Rock beat him convincingly, hell Rock survived a run in, and in general when they were on screen. Punk looked like a guy who belonged in the front row drinking a beer and eating nachos. Randy destroyed him. He wasn't truly played up as Trips equal. And let's be real here, the guy for months on ended struggled with the likes of Kofi, his strikes being shook off jobber fodder, and you expect to sell his lil pudgy ass whose never dominated anyone to be able to hurt Brock Lesnar!!! The same Brock Lesnar that destroyed Triple H, snapped Shawn's arm like a twig, and reduced Cena to a pulp who had to resort to using a chain after returning from UFC? Fuck out of here.
Bryan went from a guy who in his career, lets be real here, made NXT and then went to nexus to be fired. He returned hot, has a little feud with Miz before winning mitb. His mitb run was a joke, his same fans and loyalists didnt even support the guy even when he won the world title. He got squashed in 18seconds for the World Heavyweight Title at WrestleMania, that's Chavo jobber shit. From there a yes movement started, but it's just a chant like what, it's not Hulkamania or a chainggang, animals unleashed, 619 type movement where everything he does sells and draws. But I digress, he's teamed with Kane and called the weakest link, loses the titles, and does some random shield ass kicking with even numbers on sd. Then you expect to sell him, a guy who has been called the weak link, never even had great showings for a prolonged period as a singles guy where he's billed as a master technician or guy who can kick your ass and break you down in a ring, to Bill him against John Cena at the second biggest ppv of the year? And to cherry on top it, you have Cena hand pick him after a reality show comes out and shows then both dating the Bella Twins and him not even being strong enough to chop a freaking log?
By every means, Punk and Bryan didnt fit their billing. It would have been fine at Battleground. But at SummerSlam its bs to try and tell people in Hollywood, at Staples Center, where you've rolled out a red carpet, have Access Hollywood there, and countless celebs these are the guys who can kick the ass of Jobn Cena and Brock Lesnar. That's not something you buy into on the second biggest stage there is. A guy like Trips, Show, Kane, RVD fighting Brock sure. A triple threat at best with Punk and Bryan against Cena where its possible Cena can lose without being pinned as the midgets beat one another sure. You can't say its viable to suspend your disbelief when Punk and Bryan are fodder to real elites every time in their career and lacked momentum, you just can't.