In urban and suburban areas, it benefits society to have more development on a given piece of land. Taxing the land only does not mean the nominal tax liability goes down. Taxing the land only means the land owner is incentivized to do something with the land. The more productive the use, the better for their bottom line, and the better for society.

Easiest example is having an empty lot or a detached single family homes taking up 0.2 acre lots in the middle of a city that could house 10x as many people on the land. Right now, leaving it underutilized makes it a cheap savings account for the landowner. Developing it is work. So let's incentivize the development taxing the land only (can be the same or more), so that the only way it makes sense to control that land is to do something sufficiently useful with it.