Zoning, like anything else, is not a black and white thing. No zoning would be bad, and overly strict zoning is also bad. There is a happy medium: "good" zoning. I know, I know, this is truly insightful and brilliant, thank you, you are too kind.
*ahem* This is important to point out for this discussion: the alternative to zoning is not "no zoning." It is not accurate to say Houston has no land use controls; Houston just does it in a different way, through private deeds and encumbrances enforced by the government. See this
article. So the real question is: do you want legislated voting, or do you want private land use controls that you can only control to the extent that you have the economic means to do so? Or do you simply want no land use control at all? (I think we can all agree that would silly, as it would involve preventing private parties from controlling the use of their own property.) That is the real question.
Anyway, stopping the factory from being built next to the house you currently have a 30 year mortgage on is a good thing, albeit a far fetched example. Public zoning gives property owners (and renters, to an extent) transparent predictability, which is important for property values; if you have absolutely no clue what is going to be built in that open field next to your house, do you really want to spend your savings and encumber yourself and your family for a significant portion of your remaining years on this earth hoping that a 7 story apartment building is not built there that blocks your nice view of the ocean? Or a morgue? Or a bar? Or a strip club? If there is a private encumbrance that needs to be negotiated, or that was already negotiated Houston style, it might not be as easy to either re-negotiate it or figure out what it says, as opposed to a public zoning code you can go look up online.
That's the extreme example. And yes it can happen. The more common example however is density; e.g., a residential zone can have "light commercial" and low density housing, which is not just important for property values, it is important for government planning for things like: how many parking spaces they need, the adequacy of thoroughfares for traffic planning, plumbing, electricity, and things like that. Zoning laws typically follow a "general plan" which is a document a municipality makes once ever few decades to literally plan how their city or county will look. There are bad ones, and there are good ones. As History Buff mentioned, there are trends right now towards more "mixed use" to encourage walking, biking, and public transit, but owing to the extended timeframes (and the fact that a lot of places are, well, already built up) more "progressive" (e.g. forward thinking, not political) communities are still a ways away.