To most men, dancing is a flimsy form of art, not very manly and definitely not the first choice of "extra curricular activity" or "hobby" to take on. In my 3+ years of dancing, I have come across more guys who looked down upon dancing and had very biased opinions of "men on the dance floor" than those who considered dancing as much a sport as any other.
Men, in general, prefer to be involved in sports such as football and wrestling and forms of entertainment such as drinking and smoking and function with a pre-determined notion that dancing should be left for the opposite sex to concur. Only the few men who are willing to shed that misconception and try their limits on the dance floor are fortunate enough to realize how much skill, talent and discipline it takes to be a great dancer.
Even though I speak of "men" as a mix of all age groups and social statuses, I believe that it is more difficult to get a younger guy to join a dance class and on the dance floor than a more matured man. I say this with much conviction since most of the dance classes and social dances I have attended (In the USA and Asia), consist mostly of older men and women (especially older men). This could be different in each country, state and city and also very dependent on the style of dancing (ex. Standard dances vs Latin etc.) but I don't think I am too much off tangent to assume this as a general observation.
For all the women who are trying hard to get their male friends/partners/significant others on the dance floor, here are a few more tricks you can try.
1. First and foremost, tell your partner that it doesn't matter what he can or cannot do, how many tricks he has up his sleeve and how many achievements he has in his life, if he cannot dance then he is not "complete". Tell him that being able to take a lady to the dance floor with confidence is one of the basic elements of "manhood" and being "manly" :)
2. My dance teacher always used to say "in a world where the battle of the sexes are becoming more obvious, dancing is the only time the men get to lead and the women are compelled to follow". Try this line next time on your partner, maybe his boosted ego and a chance to "lead" will get him off the couch and the TV and onto the dance floor.
3. Suggest a few easy dance videos / instructional videos for your partner to watch. Youtube is also a great source to get your hands on a variety of basic video clips for free. This will not only put him at ease and build confidence but also will be a great tool and guide to determine what kind of dancing will be most suitable to both your styles and purpose.
4. Dance at home with your partner if he is too shy to dance in a class on his first attempt. Make him try some dance moves at home when no one is watching! Guys would be surprised to find out the extent of their capabilities.
5. Encourage your male partner to try dancing (in a beginners group class or even at home and different types of dancing) as a form of exercise and recreation if he is not willing to put time and effort into serious dancing at first. Once they get the hang of it and learn to be less self-conscious you might be able to convince him to take some lessons with you and maybe even take dancing to the next level.
To all the men who are averse to dancing should first come to the realization that looking graceful and elegant on the dance floor comes with a lot of practice, effort and discipline and that the dance floor is a space where you can take control, be in charge and show your audience everything your made of. It's a space, time and opportunity for all men to be more manly. Not less.
To all the women who are eager to get their men on the dance floor, try the above and be patient. The men will eventually come around.