Lack of proper punctuation can lead to serious misunderstandings.

"Let's eat, Jerry." "Let's eat Jerry."

"How do you do, Sally?" "How do you do Sally?"

And the infamous "Eats shoots and leaves." vs. "Eats, shoots, and leaves."

I suppose an excellent writer could display his skill by still conveying the right meaning without punctuation, but that just seems like showing off to me, sort of like trying to write a whole book without the letter "f." The art of writing would suffer.

To me, a really great novelist conveys not only the words and thoughts, but also the rhythm of his characters' speech. Raymond Chandler would be a prime example of that. Can't see how that can be done well without punctuation. It was developed over the centuries for very good reasons.