First, a silly reason: I got to introduce myself as "student doctor so-and-so," and it was thrilling to hear myself say the word "doctor" before my name while introducing myself.
Second, I knocked on the door, interviewed someone, and then stepped out and charted on the encounter. In preceptorships, there's not much documentation that medical students to (at least, not in my experience). But here, I got to pretend that I alone was responsible for the medicolegal documentation of what that patient had and needed. Cool, eh?
Third, I got to use my (still embryonic) clinical acumen to decide which questions to ask the patient, and what parts of the physical exam I should do. Even though during my feedback session I discovered that I'd missed some things that were important, I still listed a good differential diagnosis.