Looking Like People

"Your characters talk and act like people, but they don't look like people," my fiction writing class told me last week.  This constructive criticism has stuck in my head since then. 

It's true: I rarely describe the physical features of my characters.  Maybe it's because even though I'm a visual learned I struggle to describe real people much less made-up people.  There are almost a million 5'4" girls with light brown hair.  Maybe it's because I find writing physical description to be boring.  "Her dyed red hair fell in her face covering her hazel eyes" lameness.  Maybe it's because when I'm reading I envision the characters my own way and don't like being told I'm wrong.
"But we want to see the characters the way you see them," my professor told me.

My question is: Does it matter?  If it's vital that a character has curly, dark brown hair looks like she jumped out of a Jane Austen novel, then, yes, of course I'll mention it.  But does every character, or even the main character, need to be accompanied by a physical description?

Elizabeth says yes.  Otherwise they're just voices.
Nikki says she's stop reading if they weren't described.
Without looking up from the book she was reading, Amy nodded.

I remember as a fourth grader reading The Lion, The Witch, and The Wardrobe before watching the movie.  Afterwards, the teacher asked us what we thought.

One student (I wish it was me...) said, "I liked the pictures in the book better."

I gave my protagonist strawberry blonde hair just to appease my classmates.  But deep down inside I wonder.  Does it matter to you if you know I'm so skinny I disappear if I turn sideways, my hands are so chapped they're bloody, and my not-quite-shoulder-length dirty blonde hair spends a majority of it's time in a three-quarters pony tail?

<>< Katie