Yeah because tbh if I went anywhere and someone went "let's have a line dance!" I take that as my cue to leave. I think there just may be less people into swing and line dancing then op wants to admit. I mean go to a club or the right type of bar and you can find dancing no problem, even line.
Though every wedding I have been to there was at least some dancing, though I would guess it depends on the size and the people, if they don't wanna dance they don't gotta dance. Not to mention that in most weddings I have been to the music is more intended for couples dancing, which makes dancing even more awkward if you don't have said couple to dance with, excluding a portion of people I would assume.