I have written before on this blog about one of my fundamental criteria for teaching writing--if you don't look forward to reading what they wrote, you're doing the wrong thing. Well, if you ask the kind of question I posed above, I can't imagine you wouldn't be interested in what your students write. If you're a WPA, you'll get a plethora of information about your program-as well as advice from students on how to teach or not teach writing.
Let me pose this as a question for WPAs: why not ask students about their attitudes toward writing and how their experience in X course influenced their attitudes? How about getting a significant number of your teachers to pose the same kind of question and then getting together to review what students said about the value of what they learned? I'm thinking this kind of assessment strategy is more informative than one that poses a writing task (or portfolio project) and then has teachers read and rank the quality of responses according to a rubric. Rather than test or rank students, we should interview them.