I also have a theory that the IWC have things that they are precondition to hate. One being big muscle guys that can't go in the ring. Another being guys that seem to have the backing of the company and get the 'undeserved push'. And lastly faces that are seemingly 'unbeatable'.
The funny thing is that Ryback at first glance it might seem Ryback is all three of these things. But the reality is he is none of them. He is a big muscly guy, yes, but he can go in the ring. When he's been put in the main event matches, he's delivered. He has been in the ring with good guys on all four occasions (Cell, 3 way at Survivor Series, and both TLCs). But he got the job done, and I'm not generally a star ratings guy, but to me the average for all 4 of those matches is roughly 3 and a half stars. You can't really argue with that record.
As for being a company guy and getting the monster push. Well he's been around the developmental and on WWE's radar since 2004, so he's nearly a decade in the making. WWE didn't just pull this guy out of a gym, liked his look and then straped a rocket to his ass, but have ensured that he honed his craft and made sure he was ready before giving him the big TV exposure. As for the push, well for months and months, all he was doing was squashing local guys. As far as I'm concerned, that's not much of a push. If people can remember, at roughly the same time, there was also Brodus who had a huge undefeated streak too, and he was actually going over guys like Miz and Ziggler too, so from that perspective, he was getting a bigger push than Ryback at the time. But the difference is Ryback was getting himself over while Brodus was not (it's worth noting that gimmick may also have played apart, but nevertheless).
So I would hardly say that Ryback got a super push right out of the blocks. Rather that he was booked well, and as a result, he got over. So then he build up some momentum, and beat more important guys (Miz, Ziggler, etc.) and the big push actually came when he was put into the program with Punk. But I don't see how it can be classed as undeserved when he build up the momentum for it, he was over, and the push actually worked. Surely such facts contradict the idea of a push being 'undeserved'. The only other argument to a push being undeserved is the cliche 'paying of dues' which I actually think it's an asinine point anyway, but nevertheless, the guy had been wrestling for over a decade, so I think by anyone's standards, that's 'dues' paid.
So he's gotten his push, he's in the main event of a PPV, and he gets beat. It was a screwjob finish but he's still beaten and the streak ends. But he's still over, and there's a rematch. Beaten again, screwy finish, he's still over. Rinse and repeat, etc. So the guy has lost ALL four of his big main event matches. So much for the 'big' push. But the guy is still very much over. I'm not saying he should have won any of those matches, but simply stating that his 'big' push really isn't that big of a push.
As for being a predictable, 'superman' babyface character. He is that. He does win the vast majority of his matches. But that's exactly how he should be booked for maximum effect. Based on the way he looks, and his hard hitting style, he's pretty much the perfect unstoppable monster. So if he loses random matches for the sake of unpredictability, or he loses clean, then he loses the aura of invincibility he has. And that aura of invincibility plays into what pro wrestling is all about. 'The immovable object vs the unstoppable force' and all that. That's what the HIAC PPV did such a good buyrate. It was the heel champion vs an unstoppable monster in a cell. Something had to give. It's also the reason why The Shield are so over. Seeing the indomitable Ryback manhandled and thrown threw a table. If The Shield did that to R-Truth, then it wouldn't have been as striking as when they did it to Ryback.
tl;dr A bunch of geeks hate on based on preconceived notions about him and also don't think the first thing about what most folks like in pro wrestling.