I would rather people drive barefoot than in high heeled shoes like stilettos (or any shoe for that matter).
I've read time and again that some cops think it's illegal to drive barefoot and will ticket a barefooted driver but not someone who is wearing stilettos, which is obviously much more dangerous.
Nope. Not in Illinois or any other state. Driving barefoot is perfectly legal in all 50 states. The only exception is that it's illegal to ride a motorcycle barefoot in Alabama.
The SBL site has a very thorough discussion on that.