At some level zoning laws make sense. There are good reasons for me not to be allowed to pave my entire property on a whim, and there are good reasons that I can't just decide to run a bar out of my basement, and there are good reasons that I cannot build a 30' wall on my property line. That said, a lot of zoning is parochial nonsense.
Setbacks are my current gripe (for personal reasons, and because of this mention by Atrios). Between being able to maintain your property, not invading on a neighbor's or public space and not being a fire hazard a few feet of setback, in some cases, makes good sense. 10 - 30' (depending on zoning and structure) almost never does.
The only thing a 10' setback does is break up your property into smaller and less usable pieces. It is particularly galling to have such in a neighborhood where lots of earlier built structures are right on the property line.