Neo-Jansenists are against dancing. They are also against touching a member of the other sex unless absolutely forced to: this rules out dancing. Yes, the Cure d'Ars was against dancing, St. Francis de Sales was not overly fond of the idea, and under certain circumstances it is certainly best to avoid it. The Cure d'Ars and St. Francis de Sales' main beef with dancing seemed to be that while you were dancing, you were occupying yourself with things less worthy than, say, praying, pious deeds, or even gentle occupations about the house. Also, balls were an excellent place for vanity to fester, for envy to flourish, and for impure thoughts to take root. These two saints cautioned against dancing, but, circumstances change.
Dances are no longer balls, an event where one looks at others' dresses and becomes envious as Lady C___ has more lace on her petticoat than thou, or so-and-so-danced-with-her-and-not-with-me; dances are now more casual in nature, something attended perhaps weekly, as a recreation and social activity. (Which isn't to say that dances weren't recreational in the past, or had nothing to do with social realms - I assume they were, although I know next to nothing about dances of the 17th and 18th centuries.) The emphasis on dancing has decreased, or, dancing seems to be less important than it used to be and is now more of a recreation than an event. (Perhaps I am wrong in this, but I'm sure people will correct me if I am.)
I like dancing. I think it is a nose-thumbing to modern ideas. There is a leader and a follower - it is akin to marriage in that the man leads and the woman follows. It isn't that the one is more important than the other, but someone has to steer in order for the dance to be executed in a graceful manner. Dancing also places a deep emphasis on the role of a woman versus a man, and those roles are even essential to certain dances - like the Paso Doble (the man is a matador and the woman is the cape), or the Tango (the woman is playing hard to get and the man pursues her in a manly way).
Mark you, there is a movement to make dancing more accessible to same-sex couples, and there are now some halls that no longer welcome those who believe dancing should be between a man and a woman, but I can't image anyone, if injected with a truth serum, could deny that the tango performed by a man and a woman was not greater in beauty than that performed by a same-sex couple.
Sadly, what passes as dancing nowadays (of the b&g variety) is undeniably immoral and immodest. Ballroom and Swing dancing are making a comeback, though, and in the Bay Area, the Swing Scene is particularly good. I have been dancing for four years, now, and I love being able to render 'the "characters," as Aristotle says, and the movements of the soul, the invisible world that stirs within us.' (Maritain, Art & Scholasticism & the Frontiers of Poetry) In any case, St. Francis de Sales offers this advice on the whole thing:
So after frequenting balls you should frame pious thoughts which may counteract the dangerous impressions made by such empty pleasures on your heart. Bethink you, then-
1. That while you were dancing, soul were groaning in Hell by reasons of sins committed when similarly occupied, or in consequence thereof.
2. Remember how, at the selfsame time, many religious and other devout persons were kneeling before God, praying or praising Him. Was not their time better spent than yours?
3. Again, while you were dancing, many a soul has passed away amid sharp sufferings; thousands and tens of thousands were lying all the while on beds of anguish, some perhaps untended, unconsoled, in fevers, and all manner of painful diseases. Will you not rouse yourself to a sense of pity for them? At all events, remember that a day will come when you in your turn will lie on your bed of sickness, while others dance and make merry.
4. Bethink you that your Dear Lord, Our Lady, all the Angels and Saints, saw all that was passing. Did they not look with sorrowful pity, while your heart, capable of better things, was engrossed with such mere follies.
5. And while you were dancing time passed by, and death drew nearer. Trifle as you may, the awful dance of death must come, the real pastime of men, since therein they must, whether they will or no, pass from time to an eternity of good or evil. If you think of the matter quietly, as in God's Sight, He will suggest many a like thought, which will steady and strengthen your heart. (Introduction to the Devout Life)