I always viewed Kaioken as a martial arts technique. Like breathing helps martial artists strike harder. In the same breath Kaioken uses the user’s energy up at a much higher pace like breathing to perform a strike would. I think Kaioken though flashy, still respects the classic Dragon Ball, martial arts and techniques are important line of thinking. Even to the point one of the core themes of that arc is hard work(Goku learning new techniques) trumps natural born talent(Vegeta). But after that arc martial arts and techniques mean very little it becomes what colour is your hair with no drawbacks and the original message is lost…