I can see the OP's point. For the comic and TV series, I think the point that people are the real threat is basically a dead horse. We get it: a lot of people will do nasty things in the absence of law and order. At the same time, it's hard to tell a good story without human antagonists. Zombies are great for a feature film, but for something that last longer like a whole series, they are too dumb to be an interesting enemy even if sometimes they share similar goals with people (i.e. need food).
So yeah, I agree that the TWD's whole premise isn't really new, shocking, or even refreshing at this point but it's also what keeps it interesting.
However, I will say that it does bug me that good people get screwed over constantly without a break. I mean just look at the game, all the good characters except Clem are dead because of others. Yes, I get it the TWD is supposed to be all grim dark, but the darkness isn't very realistic. Like others have said, a lot of people won't be as antagonistic as TWD claims. But it's one of those unrealistic features that is needed to keep the entire franchise going. It's kinda like Star Trek where all shit in the universe is always thrown at Enterprise to the point people should wonder, "Man, wtf is up with their bad luck?"