William Kennedy, the man who created one of the country's most-respected public defender's offices, lost his job yesterday. The State Board of Public Defense appointed assistant county attorney William McGee as chief Hennepin County public defender. Kennedy held that job for a quarter century, during which time he built a law organization with one-hundred lawyers. While noone disputes that Kennedy was an important advocate for the poor, neither do they dispute that he could be an abrasive man. A few years ago, he filed suit for more money for his department. More recently, there were charges that Kennedy instigated an investigation of his opponent and eventual replacement. Judge Patrick Fitzgerald, who has been on the Hennepin County bench for 24 years, says Kennedy had two important traits: he was an excellent trial lawyer, and a good administrator. Judge Fitzgerald says he'd have preferred Kennedy kept his job.