If you're familiar with Edison, try to imagine making a left on Route 1 to get to the Menlo Park Mall. You'll back up traffic for hours and never get through. Now go down the road to woodbridge and picture the same thing to get either to Woodbridge Mall or Toys-R-Us, you'll sit there for hours.
There's just way too much traffic in this area to allow for left hand turns. Maybe it's because I grew up in Jersey and I find it confusing because I've always driven these roads.