I don't know why Honda came up with the locked rear axle other than just being cheap. My old Kaw ATV has a lever on the side of the engine that locks it if needed. It turns on a dime.
Just being cheap I guess. The one advantage is that it allows them to use a single disc brake on the driveshaft, which keeps it somewhat out of the mud. My Big Red was tough on rear brake pads in muddy conditions. Twin inboard discs and a rear differential would've been the best of both worlds.
