What's the Motivation Behind Writing Workshop?

I sure hope this happens to other people besides me: when you think of something after a lesson that you should have thought of before - only in this paticular case, replace lesson with unit.

Maybe someone out in the blogosphere will have an answer to this question. I was pondering my student teaching this morning, as I do from time to time when my mind drifts, and about writing workshop. What is the motivation for a student to put together a portfolio in an average English class? Theoretically, if one comes up with some really good writing prompts, students will want to write. But what if you have a student or students who just really hate writing. It would seem they should have to learn to write at a functional level, but why should they be happy about writing poetry or short stories or anything other than the essay they might have to write in college, depending on their major, and the reports they might have to write depending on their job. Usually, we can convince students that writing has some factor of coolness associated with it, but what if we can't?

So then one thinks they're being a really cool teacher encouraging students to write poetry and stories and multigenre projects in addition to the essays required by standards. But then students end up disgruntled for making them write so much.

The limited stuff I've read on writing workshops comes from three books: In the Middle by Nancie Atwell, Room 109 by Richard Kent, and A Community of Writiers by Steven Zimmerman and Harvey Daniels. Atwell works at a private school for highly motivated, gifted students. Kent teaches an elective writing course. Zimmerman and Daniels encourage workshops as well, and for all I know are pretty well rounded teachers.

So maybe writing workshop shouldn't happen in required English courses. It seems like the students who would benefit from it would lose out, but what do you do with the students who hate to write if you can't get them to love or like or endure writing? Fail them?

In my naivity I think I'm missing something? Can someone help? Maybe this never happens, maybe all students find motivation to write if they're asked the right questions - I don't know.