I can understand wanting to keep the possibilities open when it comes to what's going on outside of TWD's limited setting, I just think it would be nice if we got a little bit of an idea of what's going on elsewhere. I don't need everything broken down in detail, just a little tidbit here and there would be nice.
That goes back to the issue of the producers/writers moving away from expectations based on logic: no amount of suspension of disbelief can make audiences think the entire U.S. landscape are mirrors Rick's group, Woodbury and/or the bar room thugs. It appears the producers feel the moment that realistic option comes to the table, the entire "struggling / hanging on a thread" idea loses much of its dramatic edge, as it would give characters reasons to leave (long before the current season), and the zombie outbreak not as bad.
Hershel's farm and the small number of walkers contained in the barn also makes one wonder just how many are shuffling around; Hershel's group had to leave the property to catch random walkers, yet in all of the time before the arrival of Rick's group, there were no mass groups invading the farm.
This poses somewhat of a problem: it has been established that the walkers sense the living, and follow them until contact is made. After Hershel's group had been exploring the woods finding walkers, whatever movement/odor/energy sense used by the walkers should have set season two's conclusion in motion long before the time period in that episode, or at least a version of the invasion.
It appears walker movement/detection is changed to fit the story, without realizing the audience does not gloss over details, contradictions, etc.