Incorrect, the tunnel vision of Raikiri only backfires when you're facing an opponent who can counterattack you. If he had just used it to destroy the meteor it would work normally. In fact, I'm sure now that after Lee and company broke it in half, Kakashi certainly could have destroy the rest by running Raikiri Chain through it but Sasuke came in for dramatic effect.
Kakashi doesn't need to be a natural suiton user, your affinity is the element that easier to master and what your chakra responds to the easiest. Someone like Hiruzen, a master of all 7 elements, uses huge Suitons on par with his Katons (his affinity) and they're equally as strong because hes at a point where hes completely mastered them all. Not saying Kakashi was at that point, but that his Water Dragon definitely could have worked like Mei's.