Quoted from Rarehero:Because it's a pinball game...sometimes pinball is better with a simple narrative. If any game were to work with a simple narrative, it's TWD.
-KILL ZOMBIES!
-SURVIVE!
It features scenarios (Well Walker, prison, fish tank, etc) and language from the show (calling the zombies "Walkers", for instance). Even if it's not 100% accurate to the show, the fact that it has "The Walking Dead" title on it means something...it will attract fans of the show to play it. Even non-fans will see "The Walking Dead" and instantly understand what to do - Kill zombies & survive as long as you can.
POTC didn't feature any voices or many storypoints from the movies. Yet it's one of Stern's all-time best selling games. People see it and say "Oh, Pirates, sweet!"...they look at it...the toys are obvious (sink the ship, open the chest)...they play it and have a good time.
I think voices from the license are usually important...for example, not having Peter Cullen as the custom Optimus Prime voice in Transformers was a huge blow to the game - but he's massively iconic to the license. Are any of the human characters THAT iconic to TWD? In this case, I don't think it's a gamekiller IMO.
You can have a simple narrative, and still incorporate the characters. Rick is easily an iconic charater on the show. You could help Rick clear the prison yard (which is what he does anyway). His picture is featured prominently on the side of the pro. To me, if he's not in the game, it's simply getting much closer to being a generic zombie game with nods to the show, and not a TWD themed pinball machine.
It might not bother some people, but not having show characters will bother me. It also may be a fun game, and appeal to casual players. That's fine, I just won't be particularly interested in buying one.