I used to have essays be a part of a student's exam as well. The questions were nearly identical to the questions Bronson mentioned (which doesn't surprise me because I also am Seidokan along with IAA).
I 'stole' this idea from my teacher, who used the same questions as well. Aikido tests are great for testing physical ability (technique), but to test someone's mettle on paper is even tougher. That said, I still think there is a useful purpose served for eassy tests.
Liane, I, like others, believe tests are for the student, first and foremost. The student learns more about him-/herself that day than ever before, with any luck. Students can take the opportunity to ponder their reactions, try to understand why s/he "got so frustrated" or why s/he lost control of the attacker(s). Sensei learns about the student, too, but I believe that's secondary.