Oh, I agree there are problems with the show. Granted, I've only watched the first two seasons and I'm aware of its story from third-party accounts from friends. I also think that Zombie games can only go so far, and when you enter the dystopian aspects, its becomes a broad genre, with many other options, sure. But for a simple Z-Apocalypse game, the setting of The Walking Dead is as good as any if you don't want to go with super/mutated zombies.
There's one aspect to a Zombie world, though, I find is often overlooked: how hard it is to go for days without proper sleep, food, and water, and how badly prepared modern folks are to survive without electricity and other utilities. After a month, when the surprise factor would be well over, as you said, most people would be so tired that the shambling horde would catch up. One month in and we're talking less than 0.005% of humans alive. This is only shown when it's convenient to the story, of course, and what we mostly see in the movies is the characters emerging seasoned veterans.
Anyway, we'll probably keep disagreeing with each other about Walkers as a threat. As for the intent of the OP and the post you originally quoted, given how much noise TWD made in its first years, it could've been a RPG, just maybe a not very successful one, I guess.