I Like Feeling Stupid: Earlier this summer I read the excellent essay by Martin A. Schwartz in The Journal of Cell Science (May 20, 2008, doi: 10.1242/10.1242/jcs.033340) on "The importance of stupidity in scientific research." He describes how even very smart people might not enjoy research because they don't like feeling "stupid" all the time. (Via FemaleScienceProfessor.)
Very well put, read the whole FSP post. Unfortunately, the original The Journal of Cell Science article is behind a subscription wall, so it's available only to those of you who enjoy the privilege of a well-stocked academic library. There's a big difference between voluntarily suffering feelings of stupidity by working on hard problems and being condemned to stupidity by obsolete barriers to the free circulation of scientific information.