Public policy is to be guided by a George Carlin comedy sketch? I guess all politics is comedy (or entertainment) anyway.
Seriously, 140 years ago, then much smaller cities realized the benefits of greenbelts and parks, it would be a dark day for cities (perhaps literally, given how much trees can clear the air) if they decided to eliminate green spaces. You give something up to get something, and if you took inner green space, you would probably have to recreate it (or leave it in new development areas) somewhere else.
I just looked at the Google map of London. Why not keep the green space you have and expand into the fringe areas? Yes, it probably behooves socieity to encourage all new housing to be built at a greater density than might have been done in suburban areas previously to preserve the countryside, and I have no trouble with that debate at all. I do recall seeing a study that said the best way to limit environmental impacts is to spread out cities rather than compact them, although, I could probably find more studies saying the opposite.
Nor, do I have a problem if they end up taking out the least successful public courses for other uses, or whatever, and convert those to parks. In reality, that kind of rational land use has been happening forever in something less than the "all or nothing" type sweeping public policies like the one proposed in that article. I can't believe eliminating golf completely would benefit society at all.
And, I would be interested to see if some uses, like skateboard parks, outdoor theatres, tennis courts, etc., actually get more use at more paid rates than the golf courses they propose to replace. I use my regional jogging trails, and rarely pass more folks than I would see on a golf course on a Saturday, and I see a lot of public performance spaces that rarely ever get used, so I wouldn't be entirely sure that you get more public good, at least, not in all cases.
Short version, not every idea posted in the media (or government, LOL) is really a good one. They are often pretty one sided, including sometimes, a la Chambers Bay perhaps, or other golf, that merely trades one problem for another, because someone thinks they should be able to tell others how to live.
Obviously, my love of golf biases this opinion, but hey, golf bias is as legit a bias as any other.