It's not legit bunny hopping and it's also not very useful. If you jump, your movement becomes predictable, and if you crouch you take 2.1x damage. If you jump and crouch, any semi-decent player will probably butcher you.
There's only one time you should ever crouch. When falling, or if you're going to take explosive (not direct) damage from a weapon not made by bushido. As you take reduced damage from that.