Biker Bob, I think it may be because it can be done in under 2 mins with minimal to no thought required. Patterns may do it for some, but I think that overall, the general user is like me and far prefers actual pictures which require thought and have a nice image to reward your efforts. The best authors out there on this site by far are Serbanqq, Sparrow and Peppermint. Unfortunately Serbanqq seems to have stopped producing them which is a real shame!
Not sure why the rating at the moment is so low.