That's because there are both physical and mental aspects to dancing. I haven't done any SCD, but I know that in ballroom dance, the man has to decide on the step, lead the step while preparing the next step, maintain the technique for the step, all the while looking out for other dancers!

While I have met a few people that just really COULDN'T dance, most men are just afraid of looking like they don't know what they're doing. Of course, I counter that with "nobody else in class knows either, so you're all equal." Plus, I tell them that they get to put their arms around all sorts of ladies and their wife can't say anything about it.