There are as many answers to this question as there are tango dancers. Dancers are drawn to the music, the connection, the technical challenge, the dance's improvisational character and expressive palate (dramatic, playful, energetic, sweet, sad...). These three short documentaries provide various perspectives on the experience of social argentine tango.
The Tango Banter is a great podcast by Yelizaveta Nersesova on the dance, the culture and community of social Argentine tango. Veronica Toumanova has some thoughtful essays on learning and community in social Argentine tango.
Social tango dancers follow an etiquette known as the cógidos that developed over decades in the milongas of Buenos Aires. The códigos provide the framework (or common ground) that supports navigating milongas with respect, courtesy and ease.
This praxis focus is on social dancing (as opposed to performance or competition). Nonetheless, I'd like to share two professional performances because they demonstrate the playfulness of the dance.