The thick/thin nature of the Silk Garden and Kureyon is just part of the yarn and I think adds to the texture of it.
I don't really understand the knots, either. They always seem to show up where you don't want them. It's the one thing that bugs me about Noro. Other yarns manage to put out a skein without a knot, why not them?
It's so beautiful, though, I guess I'm willing to put up with it.