Every time this complaint rolls around I have the same reaction: Please show me all these zombie games that I have missed. Because there are plenty of games out there where zombies are an enemy, but they could just as easily be replaced with commies or nazis or robots or aliens or what have you. Zombies have shallow motives? Sure, find me a videogame where the enemy doesn't and I'll show you a rare gem. These are Not Zombie Games™, they are games which happen to include zombies. You might as well complain about a new SSX because there are ice levels in Sonic. Rye talks about an angle on zombies
here and she's pretty much spot on; if the zombie apocalypse isn't about the survivors, then it's not a piece of zombie media.
Games which are actually
about zombies are pretty smurfing rare, in fact I can think of Project Zomboid, Dead State, Dead Rising, Dead Island (debatable for the same reason), RDR: Undead Nightmare and that's it. Probably a few flash games knocking around as well.