I'd have put Daniel Bryan on there personally but meh.
The lack of Bryan is odd, yeah. Some people are saying he is legit getting overlooked on purpose (not just the poster, but in a wider WWE context) for some reason, possibly due to poor SS buyrates. In some way, I agree with it. His feud with Orton since SS was plagued by the interference of Big Show and HHH - at one point, Bryan just stopped cutting promos altogether. At the end of it all, he doesn't come away with the title. Now, he will lose to the Wyatts while being overshadowed by CM Punk.
Remember RAWs in the summer, when Bryan would open the show and then main event it, with the whole arena YES-ing throughout. It certainly feels like he's gradually being moved down the pecking order.
Sure, there are rumours that Bryan will win the title at WM or finally defeat Triple H, but I wouldn't be surprised to see him on the undercard, in a completely different angle at WM.