Lawns are an artefact of country house culture. When a gentleman's home ceased to be a castle- in the 16th century or thereabouts- he started to experiment with gardens. The word lawn- wikipedia tells me- is first recorded in its modern sense in 1540. The earliest lawns were pure one-up-manship. The householder was saying to his guest, " Look, I have so much land I can afford to keep this large expanse of it out of cultivation." In the 18th century, lawns passed into the repertoire of landscape gardeners like Lancelot "Capability" Brown- who was in the business of turning gentlemen's parks into versions of the Roman campagna as painted by Claude Lorrain. A century later as the middle classes and then the working classes became gardeners (on a smaller scale) they took over the country house aesthetic more or less entire- (this is a gross over-simplification)- and that included the lawn- no matter that a grassy sweep of half a mile looks rather more striking than a square of a few yards across.
I wouldn't dispute that lawns- as elements in a larger design- can be beautiful. Of course they can. But taken on their own they're a bit limited- monochrome and whatever is the opposite of bio-diverse. Here- on our two or three acres in Kent- we have a garden with lawns and a much larger area of former grazing land that has been allowed to develop in its own sweet way. If I'm going for an afternoon walk I pass quickly through the garden and out into the fields- where the grass grows to different lengths- some cropped by rabbits, some untouched by anything- and there are all sorts of wildflowers, weeds, brambles and fungi, plus the wildlife that goes with them. Compared to fields, lawns are sort of boring.