I Corinthians 2:2

For I determined not to know any thing among you, save Jesus Christ, and him crucified (KJV)

Then: To preach truth in Christ, believers need to throw out all cleverness and brilliant oratory because the truth can get lost in the words. Paul, fully able to compete intellectually, wants his readers to know what he did (Thiselton, p. 208-209). He got rid of the artifices, stripped down to the facts of death, burial and resurrection and offered them as the foundation for the Corinthians to use. Adding rhetorical styles takes the chance that listeners hear the witticisms and not the message of the cross.

Now: It's a good thing to attract people to hear the gospel, but let them hear the gospel and not be so enthralled with the frills that they cannot remember the teaching, only the teacher's video clips, jokes, or dramatics.

Extra source: The First Epistle to the Corinthians: a commentary on the Greek text by Anthony C. Thiselton (Eerdman, 2000) http://books.google.com/books?id=aNkcqC9bdAMC&dq=Thiselton+Corinthians&printsec=frontcover&source=bl&ots=eoboOUfSJM&sig=9hfoo_G6zvecJwOGkoKR93iL6II&hl=en&ei=ITsdS8SuCsnM8Qb1maDUAw&sa=X&oi=book_result&ct=result&resnum=4&ved=0CBUQ6AEwAw#v=onepage&q=&f=false