In most states driving barefoot is perfectly legal and will not get you into any trouble nor get you a ticket for driving barefoot.
However driving barefoot is very dangerous because your feet can slip off the brake pedal and you may not be able to stop the vehicle in time.
When you drive barefoot it is a safety concern because when you're barefoot it could cause your foot to slip off the gas or brake pedal, causing you to lose control of the vehicle.
So always wear shoes when driving just to be safe even though it's not really illegal in most states.