I would characterise Ian Dury / Madness / The Police as New Wave rather than postpunk - a blurry distinction admittedly - but New Wave is exactly as Barty characterizes it, an affirmation of ordinary life and everyday people (so an indirect line to Sly Stone and black music). And it's much more rooted in traditional musical ability. The Blockheads could really really play. The Police were proggers before they jumped on the New Wave bandwagon. Costello and the Attractions, shit hot musicians.
Whereas postpunk is a negation of ordinary life or an attempt to zoom in on the voids it papers over. "Death Disco" is transparently non-life-affirming, a subversion of disco because it's about watching your mother die, about bodies decaying -- all the grace and exuberance of the human body celebrated in dance music, withering away into nothingness. And musically with postpunk you have the more radical angularity etc through the fact that many of them were novice players and often came up with their wrong ways of playing (Peter Hook learned to play bass completely incorrectly, leading to his unique bass as baritone-guitar style)
All that's why New Wave is the "soft option" c.f. postpunk. (I personally love both just about equally).
Then again, talking about "greyscale"... Madness actually did a song called "Grey Day" about the commuter grind and the shitness of England, lines like "wish I could sink without trace" in their own way as despairing and bleak as anything in Joy Division. Most of The Police's best songs are about loneliness (cf Joy Div "Isolation"). Ian Dury's "Dance of the Screamers" is a harrowing glimpse of desperate losers in the disco who haven't a hope of finding a partner.
Perhaps New Wave is just another approach - a more approachable approach - to the same sort of subject matter. Less avant, more relatable to the pop ear. Better suited to getting the ideas across to ordinary everyday people. Radio friendly.