More than lowering wind resistance, I believe that paddling feathered will be more efficient through more fluid strokes. I find that I tend to naturally follow the proper paddling form with a feathered paddle.

The best argument for paddle feathering I’ve ever heard has to do with high-angle paddle technique. If you use low angle paddling, no feather is required because your forearms remain on the same plane. If you use high-angle paddle and if you find that your upper hand ends up almost on top of your lower hand as you plant the blade you need to feather to avoid stressing your wrists. Take your hands and put them in front of you in the high angle catch position. Now look at your forearms. They are not on the same plane, are they? To plant your blade perpendicular to the direction of movement you will need to either feather or bend your wrist.

White water paddlers should care about feather! A lot! They are the ones with the most aggressive high-angled paddle strokes!