Why is dancing so holy that it was the avoda of the Chasidim and אנשי מעשה [as per the gemara in Succah]?
It is the harmonizing of the lowest part of man - his legs, to something abstract and intangible - sound [the gemara says that there is no מעילה on sound (בקול, מראה וריח אין מעילה) because it is intangible. We also never have a ברכת הנהנין on sound even though we do even on מראה and ריח].
The only mitzva dance we have in Tanach is Dovid in front of the Aron. This is because the Aron was the meshing of the concrete form of the Aron and the supernatural quality of not taking up space [הארון אינו מן המדה].
When the concrete and physical meet the abstract and spiritual, one dances.
[מרן הגרי"ה זצ"ל]
Maybe that is why we dance before the chosson and kallah. The chosson represents in Maharalian thought צורה - pure spiritual form. His job is to learn, daven, learn, daven, learn, learn, learn and daven. The woman represents חומר - the material. Her job is to provide for the physical needs of her husband so that he can be completely [or as much as possible] devoted to spiritual pursuits. As the gemara [Yevamos 63b] relates אשכחיה רבי יוסי לאליהו אמר לו כתיב, אעשה לו עזר, במה אשה עוזרתו לאדם אמר לו אדם מביא חיטין, חיטין כוסס? פשתן, פשתן לובש? לא נמצאת מאירה עיניו ומעמידתו על רגליו
[Of course a woman also has a spirit and a man also has a body, but women are not expected to be completely immersed in abstract spirituality and men are expected to focus primarily on their minds, hearts and souls and not to allow dinner to interest them too much].
When the concrete meets the abstract, we dance.
