It appears to torture it's purchasers for their bad taste.
I apologize if the above statement offended anyone.
If you are too poor (or cheap, like me) to spend 90$+ on a pair of these, take a pair of your own jeans, cut knee panels out, get some clear table covering plastic, cut two rectangular pieces from it and sew them into your jeans.
You could probably patent them as a new design if you made them removable by using velcro to secure or release them in place.
Adding interior and exterior windshield wipers would show everyone just how creative you are, and keep your knees on display no matter what the weather! I guess installing a heater for winter weather would be helpful, too.
To be really eco-conscious, you have enough denim from the cutout knees to make a small purse or wallet. Re-use, Re-cycle and all that.