It's About … Control. (Good Reasons.)
This is really for the purpose of trying to control, as much as one can realistically expect for himself/herself, where an expected and incoming villager will place his/her house.
This is most especially useful for developed towns. People do not want incoming villagers to obstruct paths or ruin flowers (especially hybrids). And they don't want them strangely placed immediately next to bridges and near those ramps heading down to the beach.
If you check out any of my towns, I would most recommend ACNLpics followed by Foster. I controlled, as best I could (at the time of dealing with the situations), where villagers' homes could be placed. ACNLpics, which is a theme town of museum-like homes with all "Animal Crossing" villagers' pictures being displayed, was meticulously planned and executed. On Day #01, I actually outlined, with the paths, the
flow of the town. That made it easier on me for where villagers' houses could be placed.
People do this because they have pride in their efforts with developing attractive and appealing towns.
From my viewpoint, and my experience, I think "Animal Crossing: New Leaf" should have given the mayoral concept even more thought. I would have had mayors be given
zoning control. Meaning,
where homes could be built. What areas of town would be restricted only to Public Works Projects. (I would have even allowed for relocations. People would have loved
that.)
Had "Animal Crossing: New Leaf" done this ? we could have been spared all the pain with this plot setting (early game villager move-ins after Day #01) and plot resetting (developed towns' incoming villagers).
Here are a couple links: