I've never seen a non-stretch ski rope like the wakeboarding ropes. Any idea why they're still using the poly ropes?

Non-stretch is horrible for skiing, it is not forgiving enough in the course. Try running the slalom course with your wakeboard rope and you'll see what I mean!!! <img src="http://www.wakeworld.com/MB/Discus/clipart/rofl.gif" border=0>

I'm not a course skier (no acess to one) but you do hear skiers complain about cheaper ropes being too stretchy. I normally buy/use 8 or 10 section ropes from Straight Line and other high end manufacturers. I figured the goal was to have as little stretch as possible.

There is a subtle balance in ski ropes. You want to stretch your ski ropes before using them or you can do it by just skiing for a while. The balance is a little give, but not a stretchy rope. Most skiers perfer the high strand count ropes from SL or Masterline.