From Eats, Shoots & Leaves: The Zero Tolerance Approach To Punctuation by Lynne Truss, one of my favorite books:
[Punctuation] was first used by Greek dramatists two thousand years ago to guide actors between breathing points. Words strung together without punctuation recall those murky murals Rolf Harris used to paint, where you kept tilting your head and wondering what it was.
The reason it's worth standing up for punctuation is not that it's an arbitrary system of notation known only to an over-sensitive elite who have attacks of the vapours when they see it misapplied. The reason to stand up for punctuation is that without it there is no reliable way of communicating meaning. Punctuation directs you how to read, in the way musical notation directs a musician how to play.
