So, we end up with no reason at all---it just happens, so on that note for both character and viewer, there's not much hope or answer, other than to keep running...and how long can that go on before it becomes stale, or stuck in repeat mode of temporary safety, infighting, external threats, and a shock zombie attack on a main cast member?
If you are watching this show for the zombie plot then I would agree, but TWD only uses the zombie apocalypse setting as a backdrop to the main story. The main story is the interaction between the main characters and how they react when faced with the end of the world. This is why the show is so popular, not because of the zombies (although that what might have gotten people in the door).
That's the point: TWD's reason to be is horror--specifically what video games companies refer to a "survival horror," which includes human drama. however, if TWD is only using that bait with the intent of just being another relationship drama, then it will lose its audience, as they can get that with CSI, Grey's Anatomy
, or any other ensemble drama.
The reason to be cannot be used as a gimmick that's pushed aside in favor of doing what every other TV ensemble drama of the past 40 years have all done in one way or another, or ultimately, what's the point?
Like the best of Star Trek, this show rises above its own premise to be a thoroughly human drama.
Arguably, TNG's--if not the entire Rick Berman era's strongest (as in most popular) moment was The Best of Both Worlds
2-parter, which was as much about the traditional sci-fi trappings of invasion by a strange, threatening force as the drama of Picard being assimilated into the collective. The lesson there is that ST did not need to abandon strong sci-fi elements guiding a story in order to tell the so-called "human adventure" in the form of the triumph and agony of life.
They should support each other as seen in TBoBW, not one element edging the other into the background.
If you remove the governor being morbid with his scabby, dead daughter, and keeping a collection of severed heads, then what does he--and his town become? Certainly, every survivor or group does not need the ghoul factor to operate in that world (like Rick's group pre and post farm with zombie barn), but as the series moves on, it just becomes another talking head exercise if the "survival" is separated from the "horror."
TWD is not yet at that point, but it could go in that direction, if the series followed the ideas of some fans who think its only about people with problems (with each other).