Demon hunters in warcraft wouldn't be ranged... they carry around giant warglaives, it's hard for them to do stuff at ranged
Plus that's how they were portrayed in the RPG and in encounters during TBC... It'd be a pretty weird curveball for them to suddenly have the capability to be ranged fighters.
And I always felt like they dropped the ball on mail. Only the wealthiest or highest ranked soldiers wore plate. I always felt like mail on a non-tank warrior or paladin (since tanks always seemed like they'd fit that "CO" position, to me) would be appropriate.