Saying that he did not use Genjutsu because he felt it was not real, is actually not true. He rather used it on other useful elememts to make it more real, like Kurama. Secondly, even he chose to cast genjutsu, Hashirama with his skills would easily break it. It's undeniable that Genjutsu has its flaws.
Even Minato and Jiraya couldn't completely master it, because they didn't have large chakra reserves. It's not that Sasuke or any Uchiha didn't have the skills to master sage justu, it's just that he doesn't possess such large amounts of chakra.