The important thing to remember is that an RPG is a roleplaying GAME. A game should be, in its very essence, something in which everyone can have fun. A Fighter, who at higher levels becomes a useless addition to the party, won't be fun for someone playing said Fighter. Making a balanced game simply means that everyone gets a chance to shine in different ways, even if it means giving Fighters Daily powers.
Hell, saying that it creates a disassociated mechanic, does it really matter? A Wizard is simply saying that magic exists in a world and waving a hand when deciding that spells are possible. Why can't a fighter, in a fantasy world, break the concept of what a fighter can do (simply hit things with his weapon) to show superhuman affinity with his mind and body? (Achieving exploits that are impossible for the average being through a combination of perfect control of their body and sheer determination.)
Daily powers for martial classes could simply be said to cause a huge exertion over their bodies, and using those techniques more than once per day could kill them. Makes about as much sense as why Wizards could only cast certain spells once a day. (Isn't magic in most worlds unlimited? Why would the Wizard be stopped from casting as many spells as he wants every day? Oh right, game balance.)