As pointed out above, guys do dance... they just don't necessarily place "ballroom" dancing high on the priority list. I think there is a strong association between current popular music and dancing... so when a guy is listening to whomever is the current musical phenom.. he is going to want to dance to those songs. If you can show that ballroom/latin will allow them to do that, I think that might help. So my suggestion... make an association with current music and ballroom and maybe that will get more young male students interested.
When you start to really connect with a song, the natural next step is just going.. "How can I dance to this!". It is just so much better to be able to dance to songs that you can really get into.