I image there's a balance between not wanting every huge corporation in the city center but also making sure there is actually enough people in the city to make the city work. It's only a small example but my favourite sandwich shop closed in the city very recently. Even though the city is opening up again, with all the workers at home there is no lunch time rush to bolster the day's takings. How many rural bus services exist only because they can make profit shuttling people in and out of the city at the start and end of the day? I would argue that people are the easy thing to move in and out of a city, I don't think we would ever want to go back to a scenario where the city space is attractive to manufacturing again.So the car park levy worked, less cars, therefore less pollution. Why do big business need to be in city centres, moving outside the city reduces pollution, traffic and makes the city a nicer place to be.
The other benefit I suppose is that all the big buildings to house the people are already in the city, what would you do with all the empty offices after? Imagine the fight you would have to put 1% of Canary Wharf up outside some rural town
Edit: You could knock them down and put in a park I suppose, but if all the people are gone, who will pay for it and who will use it?
Quick, someone get back to trains