It's about quality of life in the form of time taken to get into the city for work, as well as how easy it is to get to sporting clubs, social activities, etc.

It's about the impact on the environment of sprawling inefficient low-density houses with large amounts of hard unnatural surfaces and exceptionally low amounts of natural shrubbery.

It's about the ability of children to gain independence and not need to be driven everywhere because it's unsafe for them to get on their bikes and ride to cricket practice or to a friend's house.

It's about the economics and physical & mental health for an individual household being able to live their life without needing to own one car per person and put up with the stressful hour-long daily commute.

Medium density housing is so much better than low density in almost every way, if the build quality is good. The only serious downside of it is noise, and modern high-quality materials and building practices basically eliminate that as a factor. We should absolutely be encouraging medium density.