I dunno. I think there's a lot of imagination anime could draw from, except it seems to keep getting dumbed down from the manga originals. (FMA and Saiyuki being two examples that spring immediately to mind.)

The thing with KKM is that I don't mind the filler, because the series itself is fluffy brain candy. Thus, the filler is less insulting than in other anime, where it detracts from an actual, serious plot.