I was at quite a few mitzvah tantzes. I dont recall any actual dancing of the chassan kallah. More like holding hands and walking back and forth. And for the record no bachurim are supposed to be there.
If you want to hock about tznius hock about the disgusting prust American minhag of having the kallah (and 50 of her friends) come in to the mens side by the dancing for quite some time. And then everyone tries to show off to the girls how awesome they dance. Pheh. Makom znus.