"Nick, if someone bought the land near your house and started an intensive pig rearing operation immediately upwind of your backyard, would you support their right to do so?"
Not sure if I am the correct person to ask, as I am embroiled in a couple "disputes" with my local regulators/bureaucrats :)
But...assuming I have lived in my house prior to your pig farm, AND the pig farm restricts the use or value of my property, I may have legal recourse in a court of law... if I can prove damage. However, if you had the pig farm first and then I built my house it becomes a different set of circumstances. A prime example in the place where I live is the people who build houses next to airports, and then decide the noise from the airplanes restricts their use of the property and demand the airport to close or change the flight schedules, etc.
I have no problem with zoning if 100% of the landowners agree to them. If someone purchases land it is up to them to find out what the zoning is, and what land use is permitted. What often happens here in my state is that after you purchase land, our fine politicians re-zone it to the detriment of the owners, and often to the benefit of some special interest group.