Nightclubs/discotheques are entertainment venues, not transportation, nor do they have any common carrier obligations, nor is there a risk of someone showing up with prepaid tickets and then having to deal with IDB because they're inadequately dressed. You're comparing apples and ball bearings.
Nightclubs are in the business of selling an "experience" or a "scene." There's a business benefit to them in controlling the "quality" of the people they let in. People say, "I want to go to "club of the moment" because of the scene, the experience, or because its the exclusive place to be seen."
Airlines are in the business of providing transportation. People don't say, "I want to fly Air France because it makes me feel like I'm part of something exclusive." They fly AF because of the price, the schedule, the non-stop route, the loyalty program, or some other tangible benefit.
I would also argue that the nightclub goer seeks a "shared" experience, and hence, the nattiness of the fellow guests may be an important component of that. I personally, have no desire to share anything with other people on an airplane, except maybe a little shared conversation.