The United Kingdom is in the grips of a housing shortage. Residential buildings, especially near to people's work places, are in short supply.
On the other hand, there are plenty of commercial buildings, and these tend to be already near to our workplaces.
Loosening up the zoning laws might allow innovative architects and developers to reuse commercial space to create whole new kinds of housing. Think about warehouse conversions and you can see that just because something was not originally intended as housing, doesn't mean it cannot be adapted.
People will have concerns about quality of housing, and future shortages of commercial zoning – and I don't pretend to have all the answers. All I know is that I see dozens of "To Let" signs for huge, central properties, standing empty – whilst developers continue to build us tiny flats on greenfield sites, miles out of town.