I never liked Slipknot, but at least the first album had a few ok songs on it. Then they went even more mainstream and sold out to the scene. Their last album has loads of industrial metal songs on it, which is the biggest way to sell out, because that's the only stuff they play in rock/metal clubs these days.
I'd respect them more if they still sounded the way they did when they started.
In fact, their very first album, before the original studio release, was quite technical.