I've never really understood the obsession with zombies. The only zombie related stuff I'm into are The Walking Dead tv show and adventure game. Still, people seem to love them which is why these games are still being made. To each his own and all that.
I don't think simplifying this game as an A to B linear experience is fair though, because that's every Mario game in a nutshell. It's what you do while getting from A to B that matters, so I agree with semi that it's longevity hangs on how fun they make the game.
No one expects the Inquisition.