I think it's because kimonos don't have a non-decorative point. Cardigans are practical, fashion hates that 
Personally the reason I hate waterfall cardigans (on me, perfectly fine if a bit dull on others) is that they're unflattering - they have loads of fabric at the front where it gets in the way and after it skims over boobs it hangs like curtains making me look fat. And at the back it hides nothing, and my bum is what needs hiding not my front.