Don’t believe everything you read. ;-) The Walking Dead (TWD) does not belong to the horror genre, nor is it science fiction. Yes, it has a fair amount of violence, but the character development is exceptional, as is the acting.
What gives it some spice is the examination of how people can be torn between survival and doing what is right; how small groups organize themselves in the complete absence of a central government or authority; the potentially corrupting effect of violence; how people can deal not only with the death of a loved one, but that loved one immediately transforming into a deadly enemy.
Regarding plausibility, with the way the country and the world is going, unfortunately, except for the last bit and of course the absence of zombies, I think the rest is entirely plausible - one reason I find it so fascinating. In the series, zombies in fact are quite easy to defend against and are not the real danger - other humans are.
Give it a trial viewing sometime!
“The character development is exceptional”
And for me that is the mark of a good show or movie.
The world is overly fascinated with car crashes explosions and Computer animation.
Give me a good plot with lots of character development anytime.