If there is no business model and no one wants to pay, what then? We'd have a lot of vacant properties that would need to be renovated by the city. We see this in lots of places in Germany already, where there simply aren't buyers (because of demographics, primarily). Further, if you devalue properties with such a law, then you'd have a credit/dept property - landlords couldn't pay their dept, if property prices devalue by state law. Lastly, no one would build properties anymore under such a law.

.. Cities also rely quite a bit on property and real estate transfer taxes. By reducing property values, cities destroy their own tax base while needing lots of additional money to renovate state-acquired, vacant properties.