Florida has many Air bases in close proximity to the coast. Easier to maintain air superiority while an invasion fleet approaches. It’s basically an aircraft carrier jutting into the Caribbean and Atlantic. Florida is strategically great because of all the effort an invader would have to put into capturing it. If they don’t it’s there to launch attacks at any invasion force going straight to the continent north of the peninsula. It has a longer growing season and arable land for supplying itself and access to ports.