Imagine living somewhere that people who work service or retail jobs (or nursing or teaching or all manner of underpaid but essential professions) can also afford to live!
Because it means that you don't get areas of extremes. (well not as much.)
It also means that local services can't be compartmentalised so that only rich people get decent services.
For example, southwark uses the same police force to cover the southbank (cultural centre) the £5m apartment blocks, as well as the shithole council estates (well they aren't shitholes anymore.)
Imagine living somewhere that people who work service or retail jobs (or nursing or teaching or all manner of underpaid but essential professions) can also afford to live!