I think there are a lot of people out there who don't really "get" lunging, and they use it (or think it's used) just to take the edge off a spirited horse, get the bucks out before riding, etc.
And those same people will put a lunge line on the horse and chase it in an unbalanced, banking-to-the-inside, whip-cracking, frenzied, dirt-flying-everywhere circle until the horse has worn itself out to a satisfactory level. Then they get on and ride and have to fix the horse's tendency to want to speed up in order to balance itself.
I'm not in that camp. I believe lunging (when done well and with a "plan") can be very useful for developing balance, rhythm, and it's great for teaching voice commands. I don't really like lunging exclusively
in a round pen because I don't want the horse to "use" that barrier to guide its direction.
I've seen some horses that have been round-penned so much that, if you take that outside wall away from them and lunge them in a larger arena or open area, they don't know what to do with the back half of their body. They're usually the same horses that have only experienced "lunging" as what I described above - being "chased in a circle" until they were worn out, but having learned nothing else from the experience.
Personally, I don't like having a horse that turns in to face me all the time. When I lunge my horse, and I tell him to "whoa," he stops on the circle and waits. Sometimes I'll have him move on again. Sometimes I'll walk out to him and do a full walk around him while he stands there (good practice for ground-tying). Sometimes I'll pat him on the neck for a job well done. Sometimes I will change the setup of the lunge line and begin working him in the other direction. But in all cases, he stands and waits for further instruction.
Lunging is just one of those things that, to me, works well when it's done well. And it's useless or even harmful if it's done poorly.
But at some point, if you're going to use that horse as a riding horse, you do have to actually get in the saddle and learn how to deal with a horse that hasn't had all of the "bucks" lunged out of him.