According to Thorstein Vebelen, a lawn is merely status symbol, a display of conspicuous expenditure meant to demonstrate that its owner can afford to waste in mere display what might be used to produce wheat or vegetables. Alternately, a lawn can also demonstrate that beauty may be its own excuse for being.
If we have any doubts an experiment might be worthwhile. Lie down upon your lawn to see what happens. And while I would not advise that all lawns be surrendered to dandelions, I would suggest that you ask yourself, when one of these gay little miracles raises its flower toward the sun, whether you reach for the weed killer without first remembering Whitman's tribute:
"Simple and fresh and fair from winter's clothes emerging
As if no artifice of fashion, business, politics, had ever been,
Forth from its sunny nook of sheltered grass--innocent, golden, calm as the dawn,
The spring's first dandelion shows its trustful face."
-Joseph Wood Krutch