Those were the favs of my main art professor, too. He was really into lines, and they both do great ones. Although it is possible that you need to be quite the art geek to be opinionated about awesome lines vs. just plain old lines.
That's really cool! My background is in lit, but I had the good luck of falling for a talented artist (whose specialty happens to be line work). I've learned a lot from her over the years but still not enough to be very opinionated about the quality of lines. Klee and Kandinsky just pop off the page to me. When I look at their pieces that best resonate with me, it's like looking at a small section of nature and understanding how full of live it is - and how much is going on that you can't see. I'm guessing a lot of people have similar experiences with different artists, and I love reading/hearing glowing reactions to artists I "don't get," because I usually learn a lot about both the artist and the writer/speaker.