I probably phrased it wrong. I feel there are better ways to do cardio and strength training than a KB. You can achieve both with it, but I think there are better ways. They are a great supplementary tool but I would rather do some interval training on the run or on a bike than with a KB. Personally I get more out of those sessions. And with lifting, I would rather stick to the basics like WSFSB program to increase strength.
I use KB's occassionally and have a set from 8 - 40kg in my personal gym and use them when I am in the mood for something different.