Cogito, the logical result of what you're saying is the unrestrained growth of towns and cities, until there is no difference between city suburbs and rural villages, and no agricultural land.
That would have devastating effects on the tourist industry and on our rural economies. Not to mention a huge reduction in the quality of our lives.
It's not as simple as homes versus grass. We need both. But most of all, we need to stop the population rising so fast. (I have no idea how you do that, btw).
It seems to me as if the government is going about it the wrong way. What they should be doing first, imo, is consulting with local people about what is actually needed in their area. Then they should check out the unoccupied houses and flats. Then they should allow companies to build on brown field sites. Finally, they should sit back and assess the situation again.
Even if you (anyone, not just Cogito) don't fancy going youth hostelling/ hiking/camping, or value the fresh air and peace of the countryside, does that mean you want to stop others enjoying these things? If the National Trust don't protect our green spaces, who will?