Actually, dance floors aren't bad in terms of PU. They are not suited for Mystery's approach to gaming, but they are real winners for others.
A friend of mine uses the dance floor obsessively, effectively proving point 1 of your post dead wrong. He has ALL control of the interaction, even though he dances like sh1t! He is very direct and pulls girls consistantly using the dance floor as a state-building tool.
When I go to a club I will go to a dance floor simply because I love to tune out the rest of the world. It is where I do all my state work. I will choose to dance alone at all times and almost never look at anyone. I am in my own world. It occasionally happens that I am approached on the dance floor and when it does I pull in the girl waist to waist IMMEDIATELY, have her lean in to speak directly into my ear. I briefly say something like "let's talk later, this is a dance floor," and then push her away again. I display my confidence and I don't give a sh1t for the ego-bitches; I am indifferent to them. When they look, I smile and turn away. I just dance. Effectively countering you point # 6. I am in the zone. And I re-open the girl later.
I view the dance floor as a place where I can go to clear out my head and tune in my state. By dancing, and dancing only.
One of my favorite things to do on the dance floor is to play imaginary hacky sack, preferrably with the friend I mentioned earlier. It's hilarious, and always draws EC and AI's from girls on or near the dance floor.
As for ejecting from the dance floor in style: No matter what has happened out there, I will open someone as I leave the dance floor. Doing this, I establish more social proof, which underlines my social value = dhv.
EVERY setting holds possibilities. Look for them.