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because your wrist is dropped.
This actually helps. Your wrist drops, this leads to your elbows dropping, which carries on through the arm and into the torso. Same with your legs: drop your heels, bend your knees. Net result, your centre of gravity drops and is more "in" the bike, rather than above it. All helps with stability when riding off road. See also: longer, slacker, lower...
Really? I was reading a lot about rotating them forward to avoid wrist pain, due to compression when your hands/wrists/forearms aren’t straight because your wrist is dropped. To the floor may be an exaggeration, but I needed them rotated to keep my wrists at the correct angle.