Lisa was an inspiring character. We all laughed at Homer and Bart but we wanted to be Lisa, with her diligence and smarts and musical ability. I think that counts for more than how many words she said.
Maybe for you, but growing up my friends and I all wanted to be cool and rebellious Bart. I found Lisa to be one of the most dull characters in the series, and most episodes that focus on her to be on the boring side.