Ignorance I suppose. I find SL to be extremely stable and it does everything I need it to do. I have been somewhat put-off by criticisms of Lion that I have read, here and elsewhere (i.e., problems encountered with Mail, network connectivity, stability, etc. To reiterate, I have no hands-on experience, just stuff I've read). Plus the whole backwards scrolling and gestures thing, and the listing toward iOS-type orientation.
Plus the fact that I've never considered the Lion to be a true feline (is social, lives and hunts in packs, etc., cats don't do that), and I'm partial to felines