You know, you're exactly right. I drew the figure alone about three months ago, and not long after I felt the piece was missing something, and whatever I put into the background never satisfied me. I finally settled with the text boxes here, which also never sat well with me.
Looking at it now after reading your review, though, I couldn't agree more. The boxes are indeed superfluous, and detract from the rest of the drawing. I guess I was just afraid without some text to explain it, the punchline behind a doctor with a briefcase for a head would've been too obscure for most people, and in the end I choked.

I'll definitely keep these things in mind in my future works.