Pretty crucial.
Once you herioc leap. Whilst in 'mid-air "delay animation" ' you can be rooted in place, you can attack etc in the root position, but when root duration has ended, you get "teleported" to your herioc leap position, which can really screw you up.
Look at it like this;
You HL to enemy healer (arena-wise) to fear, you get rooted in mid-air, healer run somewhere else. Root ends, you get teleported to your HL position. Unable to cc the healer with whatever, fear etc.