I'm not sure why the idea of it makes me feel squirmy. Lots of readers thought the students' time would be better spent writing academic-type essays. I don't agree with that but still . . . squirmy. My comment on it:
In my many years of teaching, I found that students who did a great deal of personal writing were also much better academic writers. They had a clearer voice, a more integral sense of organization, and a much more fluent, readable style.
I got some of the best writing from students with this assignment: "Write about something you hated doing as a kid."