Hillel was not a Rabbi because he lived before Rabbinic Judaism. He is sometimes referred to as Hillel the elder, but there are lots of famous Rabbis you could use instead.
I think the term rabbi with reference to Hillel is actually a bit of an anachronism. I agree with Daniel21 on this one; this is a misapplication of the title based on a simplistic understanding of Jewish titles and positions (all due respect). Hillel specifically is most often referred to with no title at all as opposed to many other Jewish scholars and teachers.
Absolutely! Shame on people who ingest popular culture like The Simpsons. Now I'm going to go home to my mansion and read Immanuel Kant and Socrates and thank the heavens that I'm not a plebeian. Popular art that brings happiness to millions? Garbage. People who aren't in the intellectual elite deserve to be unhappy, what what!