I hadn't seen the statues in decades, so I just looked at it online. Far more famous and impressive figures are the norm, so I can understand why they want to change the statue. The other statue is Gorrie (the guy who invented air conditioning), so slim pickings may be why Smith was chosen. Aside from Osceola, I can't think of a Florida candidate with the same national fame level as most of the other statues. Founding Fathers, Presidents, and trailblazers seems to be the norm. The person has to be dead, a resident of the state represented, and have been "illustrious for their historic renown or for distinguished civic or military services".
Don't think it is an anti-Confederacy issue, as Jefferson Davis, Robert E. Lee, and several others who served in the Confederacy are statues. Alabama just changed one of its statues from Jabez Lamar Monroe Curry to Helen Keller in 2009. Guessing that Keller being their choice for the quarter in 2003 had something to do with the change.
The National Statuary Hall Collection | Architect of the Capitol | United States Capitol