Sorry to all the crappy players out there. Challenge is one of the biggest parts of a level to me, so I tend to make levels that are, well, challenging.
Well, it's one of the awesome features of KS that it allows for a huge variety of play styles & difficulty levels, so there's something for just about everyone. People like you and Purple Pineapple get the Very Hard to Lunatic levels you like, and LoCP members have Easy to Normal levels we can actually get through. (Plus there's always the option of skipping past too-hard levels in the editor, or using the cheat, but that's never the same IMO.)
Of course there are some levels, like Don't Eat the Mushroom, that have enough of a balance between challenge and playability -- in addition to awesome level concept and execution, in the case of DEtM -- that everyone can enjoy them.
Maybe I'll see if I can make super-hard versions of at least some of my levels, the reverse of what egomassive did with A Knytt in Time... I'd need beta assistance from hard-level fans, though, as I really can't distinguish between Hard, Very Hard, Lunatic and Wait No That's Impossible!