You would think they'd eventually run out of zombies that could threaten them.
Well, it's been a pretty long time since the zombies were a major threat. Even in that arc a year or two back where they managed to push down the fence around the Community, they wound up being dispatched pretty quickly.
They've kinda reached "Watch out fer snakes!" levels at this point; they're dangerous but if you take the proper precautions you stand a pretty good chance of making it out. (The current arc has had the first deaths of any major character since [spoiler] Dale [/spoiler], which was, Jesus, a third of the series ago now, and THAT was the first major character death since #50. ...I guess there was [spoiler] Morgan [/spoiler] back in #82, but I don't think he quite counts as a major character.)
Pretty much since they got to the prison, the series has emphasized other humans, not zombies, as the biggest threat and enemy. The book's not really ABOUT zombies; it's about the collapse of civilization, and a zombie outbreak just happens to be the trope Kirkman chose as the catalyst for that collapse.
It's been observed before, and none-too-subtly, but it probably bears repeating that the Walking Dead referred to in the title are not the zombies.
I mean, yeah, 250 million people in the US alone, but I'm pretty sure that number's gone down a significant amount since day 1. To say nothing of zombies that exist in isolated areas.
The book's largely focused on population centers, which makes a certain amount of sense given that the cast still needs to scavenge supplies. (They've talked about learning to make their own bullets but it hasn't happened yet; medicine and gasoline are another matter altogether and there's a pretty constant need for that stuff. The story hasn't gotten to the point where the characters have to start seriously contending with those things no longer working because too much time has passed.)
That said, yeah, it gets a little too convenient when a zombie herd just rolls through somewhere remote like Hershel's Farm for the express purpose of shaking shit up and forcing them to go back on the road again.
Was there ever any explanation about how long the corpses can keep moving before they rot away? Or are these the magical kind that ignore entropy?
Nothing much along those lines yet; IIRC they spotted a zombie that seemed like it was "sick" or otherwise less able than the others a year or two back but they haven't had much time to follow up. There have been a couple attempts to capture some for study but, as you might expect, they haven't ended well.
I think the entire storyline up to this point has taken about two years in-universe. There are hints that they're starting to bump up against entropy (bullets and canned food harder to come by) but they're still on the cusp. (And Kirkman may take some creative license with things like just how long it takes for gasoline to go bad; this is a guy who had a recurring theme about people not knowing the exact date up until someone in the lettercol pointed out that in a group this size SOMEBODY should have a fucking digital watch with a battery that's still good.)
That's really the thing that gets me about Walking Dead. The couple times I got interested in actually reading it I checked out a spoiler summary (I do this a lot). Few things turn me off a story like a soap-operatic neverending aimlessness and I really got that vibe in a big way from this series.
Even Love and Rockets?
Yeah, I'd certainly say that's the biggest weakness of Walking Dead; up to this point it's followed a pretty predictable pattern of "Wander around, meet new characters, lose a few along the way, find a place that seems safe, stay there until it starts to get boring, get chased out by zombies or rednecks (who also thin out the ballooning cast a bit), go back to step 1." The current arc, as I've said, is a pretty clear mirror of the Prison/Governor arc (coming to TV this fall!) and I'm hoping Kirkman finds something to do differently this time. (I'm thinking Rick and co manage to take out Negan with guerilla tactics and manage to stay in the Community, instead of being chased out yet again.)
There have been a couple of times I've come near to dropping it (there were two straight issues of graphic rape in the Governor arc) but so far Kirkman's managed to pull back from the brink and do something interesting each time.
He's also managed to keep a story going that actually AFFECTS me in a way few comics do; #100 was another issue that really got my adrenaline pumping. I don't honestly know how much of that is because of the tense pacing and the graphic violence and how much is because of the character-building -- I suspect that the same sequence would have had less of an impact if it had been one of the newer characters. (Abraham's group is really the most recent addition to the cast that I actually have any emotional attachment to, and that was nearly half the series ago. [spoiler]And even then, when Abraham got an arrow through the eye two months ago, I shrugged more than I gasped.[/spoiler])
The series is rapidly running out of characters I have a connection to. It's possible that, if Kirkman takes some time to build up some of the new cast, I could become as attached to them as I have to some of the veterans -- but it's also possible that the series has reached a point where I just see every new character as lunchmeat and I'll never be as attached to, say, Holly or Dr. Cloyd as I am to Andrea or even Eugene.
That's an interesting thing to explore in and of itself, though -- the reader adapting to the situation and becoming callous. Because that is, after all, what the book is all about.
Dunno. The book IS certainly formulaic, but I still feel like it's got interesting things it hasn't said yet and interesting avenues it hasn't explored yet. I like to think there's some very interesting stuff still coming and Kirkman and Adlard aren't just running on fumes and shock value.