You are absolutely right of course, and initially that is EXACTLY what you would want to do, because it would be easy to build, cheap, and the resources to do it would be plentiful. It would work great for quite a while too. But as time passes a base/settlement will become larger and more developed, more people move in, noise levels increase, etc. Its going to start drawing a lot more attention from both the undead and the living.
Eventually, that wood palisade just won’t cut it anymore and upgrading will become more of a necessity, by which time the inhabitants should be well established enough that procuring materials and labor to build a stone or concrete wall won’t be nearly as much as an obstruction as it would be for a lone survivor or a small group of 2-8 people.
I personally have 11 followers at my base already, and 45 or more sitting at an apartment complex waiting for me to transport them back (there were enough scattered around the place it was difficult to get a head count, I suspect there may be as many as 100 there). Manpower and resource procurement would not be an issue for players like myself getting into the late game.
