I wouldn't want ANY of the empty acres to be built on before all the long term empty/abandoned houses had been put back onto the market.
Then developers can look at brown field and infill sites, develop them if there is still a local need.
Where I live developers are being allowed to take green fields and turn them into housing estates. Great for people who want to move out of the local larger urban areas and to buy/rent comparatively cheaply. But utterly shite for everyone as nobody really listens when locals explain that the water table, the roads, schools, GP surgeries and all other infrastructure won't be able to cope with the increased numbers of people.
We now have about 2000 new homes mooted here - neighbouring larger villages have similar numbers, we guesstimate that there could be almost 10,000 additional homes in the pipeline, all heading for the one road into the nearest city. 1 school, 1 GP surgery all full. The roads are already gridlocked in rush hour, and that's AFTER the total rebuild of one roundabout to ease the jam.
We have no police. Despite the population growing our town, yes town , isn't deemed big enough to have any real police presence. We have an ageing population and the nearest hospital is 10 miles away, along country roads, it takes 30 minutes minimum for any emergency service to get here.
None of the county development includes improving any of the infrastructure out here.
So I'd be out campaigning for Her Maj and other landowners to keep their land empty. Use it for farming, leisure, whatever. But don't imagine that 'all that space' would be better used for housing, at least not without properly looking at the local infrastructure.
Oh, add to the above the months of road closures, 40 mile detours and increased accident rates when water, gas, electricity and broadband all go in separately. And then the further misery of the roads with all those holes and patches caused by the works and the increased heavy vehicle access.
Green space is often still green for good reason!