I believe that the controversy over gentrification (or what I perceive "gentrification" to mean, at any rate) ultimately results from two incompatible beliefs about what housing is for.
Various authors I have read on this subject frame it as a conflict between market processes and restrictive zoning. Absent tight limits on new building, they argue, it would not matter if e.g. low-income regions of San Francisco become popular with affluent techies, because developers would simply add housing until all budgets are accommodated. Even though the entire city is "built up," it should be possible to meet any realistic demand by redeveloping properties here and there, and increasing overall density. Except that cities like San Francisco prevent this through restrictive zoning.
This argument invariably leads off into all kinds of side controversies. But I believe that the whole argument, itself, misses an even more fundamental issue. Our society, along with I imagine most settled societies, seems to hold two very different views of housing:
- Housing is a basic human need. Most people seem to agree that everyone should ideally have some safe, reasonably comfortable space to occupy, with access to at least basic services and amenities. Views on how to achieve it vary, considerably, but logically this implies that (within a market economy) the end goal should be reducing the cost of housing as much as possible.
- Housing is everyman's investment account. I sense that a majority, and certainly a solid majority of the politically engaged, want housing to be a reliably profitable asset for owner-occupants. Logically, this implies that the end goal should be housing costs which are high and go ever up. And indeed, we seem to have a broad consensus that buoyant house prices are almost always A Good Thing.
As a general rule, I agree that constraints on housing supply are mostly artificial, until the area under discussion gets very, very small. But it seems to me that the main driver of those constraints is not historic preservation, or knee-jerk suspicion of developers, but simply how our culture takes for granted that we should encourage precisely what those constraints produce: rising costs of housing.
Just as it seems to me that an incompatible view of desirable housing outcomes, which is perhaps less politically influential in aggregate but of much more concern to specific communities (e.g. low-income renters), is the inevitable driver of conflicts over rights, best use, etc. Many of these conflicts get defined as battles over "gentrification." In my view, though, they are largely battles over which incompatible objective for housing actually wins out.
(Disclosure: I rent, although this seems that it should not matter at the moment as I have made no policy prescriptions. One thing at a time.)