The yarn bombers have contributed to the community of Greerton by helping make the village a festive, fun place to be in winter, and they're also using the art works to fundraise for charity. To me, it's a win-win - it looks good and is achieving good things.
In our society, artistic works seem to have little value placed on them. They have no easily measurable benefits to society and so are seen by many as superfluous or a waste of money.
You can't measure the size of someone's smile upon seeing something pleasing to the eye, or put a scale on the feeling of wellbeing you get when the place you live in looks and feels beautiful.
But it doesn't make these things any less valuable.
Keep up the good work knitters. I love what you've done and I hope those that appreciate your efforts dig deep for the charities you're supporting.