Someday these "planners" will wake up and realize that if you want denser urban areas, the easiest way to achieve this is to get rid of zoning, not instituting even more complicated regulations. It's call the law of unintended consequences.
We do need zoning laws - only not the stupid ones that exist in some communities. Zoning laws are supposed to ensure that roads, schools, public services, etc. keep pace with population growth. All too often, that doesn't happen.
There are too many examples of stupid zoning laws for me to even try to list them, but my favorites are minimum lot sizes, blocking commercial use anywhere near residences, and encouraging the development of cul-de-sacs instead of street grids.