Shiism would not exist without hadiths, which proves we need hadiths, as Shiism is proven in Quran but hardly anyone would see it, due to the sorcery on the hearts, without the help of hadiths giving insight to it.
And it's the same with much of Quran, you need hadiths to gain insight to it.
And it's the same with much of Quran, you need hadiths to gain insight to it.