Sleep is important. And it is important enough to get right. If you don't sleep, you die. If you don't sleep enough, you have a bad day. If you sleep too much, you don't have less time in the day. As a species, sleeping is something everybody does pretty much every day.
It's thusly interesting that sleep disorders are so common. We should've gotten better at it by now, no? Perhaps it is my limited worldview. I don't see too many bloggers in third-world countries blogging about the great sleep they get, after all.
For myself, sleep is something I value. But I also value my time. If I could spend one hour each day sleeping less, being only slightly less well-rested, that seems like a good trade-off to me for seven hours "extra" a week.
However, I don't think polyphasic sleep is for me.