Unless, because of the costs, none of them are. And while that does no harm, if the purpose of changing the zoning was to get more housing, then it also does no good. The profitability of the conversion absolutely should be a consideration, because a tax abatement or something could effect change where simply altering zoning might not.
If the gov does not change zoning restrictions to something less restrictive, then the work will, by law, not be possible.
If they do, then it's POSSIBLE, but it's not up to gov't to MANDATE it.
Arguing that they shouldn't "loosen" the restrictions because the market _MIGHT_ determine it's still not worthwhile seems odd to me. Perhaps this is from a cultural bias.
The point of the article wasn't to make more housing required, it was to make it possible to do so. Perhaps in other countries/cultures/governments the incentives are different (market vs. gov), but this article is not that.
>Arguing that they shouldn't "loosen" the restrictions because the market _MIGHT_ determine it's still not worthwhile
Neither of those arguments are being made. The argument being made is that if the government intends to effect change in the housing market, it must concern itself with the economics, because those economics are largely determined by government policy and determine whether new housing is actually likely to get built.
If you really want to turn this into a multiday thread, then we can start with the different theorems of value; you will come to see how even theory proves it is a terrible idea to have government trying to manage for profit endeavors. But, if you just want the magic fix to the housing shortage, you should just run with deregulation.