i would say lunge for respect, and control. i only lunge at a slow gait, and do it to establish direction, and voice/body commands. i mostly use a "C" pattern and usually end up at a walk forward when doing it, moving the horse forward in front of me, as well. the "c" pattern is really good for desensitizing a horse to things he may be afraid of, lunging him between myself and the object, like the stream on our farm, or a tractor implement, until he needs a rest, and resting near the object, or in the water.
As Clinton says, if you're riding and end up ON the ground, you haven't spent enough time working FROM the ground before you got on, i speak from experience here as Paso/Mingiz can attest.
I've also learned, NEVER believe what someone else tells you a horse can/will or will not do. Trust but verify
i definately 'bond' using grooming time (not lunging), once they stand tied quietly. and i also make them move around, sometimes sidepass, sometimes back, and sometimes move the feet to stand more square or camp out. i have found the fine movement directional instructions when grooming are a good thing for the babies, especially the ones i may (someday) show in hand.
what i don't use lunging for is to wear them out before i ride. mostly, when i lunge it's a groundwork lesson time, not a riding time. i do lunge with very noisy tack if one isn't used to tack, or too young to ride.