I'm not really sure why everyone is so upset at the Rock. He worked you guys, as any good wrestler should lol. What would've sounded better to the WWE Universe coming from him?
"Finally, the Rock has come back home, but I've got some other things lined up so you won't see me again until next year."
or
"Finally, the Rock has come back home, and I'm never leaving again."
I would even argue that this absence works much better in keeping his character fresh in a time where the WWE takes everything good, waters it down, and shoves it down your throats 24/7. Even the most electrifying man in sports entertainment would get old fast in the current WWE climate.
Furthermore, Cena's loss at WM only made him a more interesting and intriguing character, especially how they built it up as a must win for him.