Ya know, I think it would have been cool if Fighters got more Fighting Styles as they advanced until they could potentially have all the PHB Fighting style by the end of their progression. The Fighting Style could have had stackable effect so you could choose to specialize by taking the same Fighting Style multiple times and improve the bonus or go for versatility. It would have made stuff like Protection (good early on, falls off when enemy gets too many attack) more popular.
Then the Fighter should just stop at level 10. There's no point in continuing afterwards.
I think 'Command' should be a closer example for what Illusions could work.