WebCT has a "paragraph" question type which allows free-form text input - a similar functionality to the Moodle "essay" type - though focused more on fairly short answers. Students enter their answers in a text box not through an HTML editor. I find this has two beneficial effects:
1) Students don't waste their time on fancy formatting;
2) The (configurable) size of the text box is an effective hint at the expected answer length.
Any chance of extending the essay type to allow this as an option?