I would disagree that TWD isn't a thinking series... I think the fact that the series setting in a zombie apocalypse is widely regarded as nothing but secondary to the story's character development is a direct contradiction to that view of the series... It's maybe not THE deepest TV show and/or dramatic story told in history, but I think it's a very intellectual and well written show... Gratuitous violence doesn't diminish that.
You could take the zombies out, and make it some other dramatic situation which the characters are in, and it would be just as good... People fixate on the zombies and the gore a little too much I think. You could center it around a major historical event like the World War I or the Fall of Rome, and get similar results I think.
I've always said it, but the zombies are really just secondary... they're like the weather.