It exists to protect the value of detached, single family homes, which is important to the owners of those homes who see their home as an important investment.

Right: it subsidizes relatively-wealthy suburban welfare queens to "protect" them from having to compete fairly for the land on the free market. The question should not be "how do we protect homeowners;" it should be "why should they be entitled to this privilege?" That goes double when that privilege comes at the expense of people who live in denser housing, people who want to live in denser housing but can't because restrictive zoning creates shortages and drives the price up, population health because sedentary lifestyles make people sicker, making poverty and homelessness worse, making climate change worse, and last(?) but not least, financial solvency of the suburb itself because single-family houses on large lots simply don't generate enough tax revenue per unit area to pay for the services and infrastructure they use.

We literally cannot afford these subsidies -- both in terms of suburban governments themselves and of society at large -- and the people benefiting from them don't deserve them anyway. It's not just unjust, it's insane and suicidal.

The "preferences" of greedy, myopic takers must be disregarded in the face of reality, regardless of how politically difficult it is.