When you think about it, a special weapon that can reflect any and all ranged attacks would be pretty overpowered... Against Mega Man, but literally nobody else, because they can just run up and body-slam Mega Man for massive damage. My pet theory is that Dr. Light either needed booze money, or he was playing favorites with his robotic children, because Mega Man seems to be built from tissue paper and duct tape and falls apart whenever someone looks at him funny, which is why he takes contact damage from pretty much everything. Although now that I think about it, so do Roll, Proto Man, and Bass when they're playable, so I guess all the Mega Man protagonists have the robot equivalent of brittle bone disease. Maybe it's in the Capcom contract they have to sign.