Zombies or no, I loves me a good post apocalypse story. Why? Let me count the ways:
1. Post apocalypse stories are often about second chances. I think the ultimate prize for any human being, the real Holy Grail, is a second chance at life. A lot of post apocalypse stories, whether intentional or not, are about just that. What would YOU do if you woke up tomorrow and everything you knew was gone, your life was a total tabula rasa, and you were constrained only by your imagination and what you are physically capable of doing? You ask me that question ten times, and I'd probably give you ten different answers. That's the power of a post-apoc story. They explore those different answers.
2. Post apoc stories are, by their very nature, politically correct. Blacks, Latinos, women, Asians, gays...they all have certain periods of time that aren't so hot for them, historically. But the apocalypse isn't the past; it's the future. A dire, bleak future where survival is the most anyone can hope for. And when the main goal is survival, who the FUCK cares what color your skin is? Yes, of course, there are still issues like that in post-apoc stories. But those issues are more clear-cut because of the whole "survival is what matters" thing. This is, really, a trait of all science fiction stories, but the apocalypse just makes it darker...and thus, in some ways, clearer.
3. There's a blend of the weird and the normal. Real wonder...the stuff that really captures hearts and minds...masterfully blends the normal with the not-normal. This is why Harry Potter is huge. This is why urban fantasy is huge. This is why superheroes are huge. Star Wars, as it often is, is the exception that proves the rule. But the apocalypse, however, is no exception, and thus apocalypses that blend what we know with what we don't know tend to be easier to digest, and thus easier to enjoy as a story. Look at the love Fallout 4's been getting. And how huge Mad Max: Fury Road was last year. The apocalypse is a harder sell because it's dirtier, darker, nastier...but that's kinda why I like it. Because life, for many, is dirty, dark, and nasty. And a story that parallels life has a higher chance of connecting with its audience.
4. The apocalypse makes normal life more interesting. This is the other side of the coin to point number three, and it's also where zombie apocalypses really intersect with me. A supermarket in Fallout 4 feels like a dungeon in D&D. Both are mazes full of treasure and danger. A baseball bat can be a weapon of justice, just as assuredly as a sword in a fantasy setting or a ray gun in a pulp sci-fi setting. A can of beans can be just as life-giving as a healing potion or a nano-bot loaded medkit. I don't need to describe what some fancy sci-fi flying car looks like...in an apocalypse, the vehicles are the same vehicles you can see out the window. Just in worse shape.
5. The apocalypse teaches us compassion and humanity. Typically one of the first themes to emerge out of any apocalyptic/survival scenario is "live together, or die alone." No one human being is an island. Everyone knows this, but some (such as myself) take it for granted. And a story about survival in an apocalypse helps reinforce this vital lesson about being human. For all of my sound and fury, I fundamentally care about people and I try to harvest as much compassion for my fellow human being as I can. Sometimes, to appreciate the light, you gotta go real dark.