P.S. Seiza never becomes "comfortable" just less excruciatingly painful
I don't know... I sometimes find it more comfortable than sitting crossleged in certain circumstances because it naturally supports my posture. I especially find it more comfortable if I've been sitting in it regularily (if I've been doing tea ceremony, etc), and have become more used to the discomfort. Of course, it still gets irritating if I sit in it for a really long time.