Well his kenjutsu style revolves around using one arm. So even if he had both again I dont think it'll make any drastic differences.Who thinks that a one-handed Sasuke has some pretty insane moves and being on par with Kinshiki Otsutsuki despite lackng another arm for more movement and sword wielding.
Who actually thinks that Sasuke would've won if he had 2 hands to fight with????
As I said there is a difference between left dominate and left prefered. The sage asked for one hand sasuke us not about to lift both of his hands. And not everyone in naruto is ambidextrous, naruto is explicutky labled as right handedWhen the sage asked both Naruto and Sasuke for their dominate hand Sasuke handed his left hand. Everyone in Naruto is probably ambidextrous.