My wife and I ran out of things to do. We got in a little rut - especially since we are still in college and cannot afford a lot of things - and were looking hard for something to do. Being dragged to a Friday night social dance was probably the best thing that anyone has ever done for us. We delayed going time after time - since we weren't sure what to expect. But eventually we caved and went. Now we are hooked (so much that my wife became a dance instructor). We love latin dancing the most (salsa, cha-cha, rumba, etc) but ballroom and swing are also fun (anything but country). I suggest you try it.
Here are some of the positive things I can think of about dancing:
1) Inexpensive entertainment that can be just a dance or a whole evening.
2) Many traveling dances (foxtrot, waltz, tango, etc) are supposed to be danced with body contact. Depending on your body shape (thin, fat, pear, etc) your thighs/pelvis/stomach/chest will be pressed up to an attractive womans's thighs/pelvis/stomach/chest. This is a VERY good way to get a relationship to the next level. Need I say more about this topic?
3) You can use it for the rest of your life. I see people in their 90's dancing beautifully - my wife has one student who is 88.
4) It comes in handy. We have two weddings on Saturday to go to. We barely know the brides and don't even know the first names of the grooms. Usually this would be a boring event, but we are now really looking forward to the receptions. Also think class reunions, cruises, nightclubs, etc.
5) It is great for your body (fun exercise, I finally got good posture gaining a full 2 inches in height from my old posture, etc).
6) Social interaction with new people is really beneficial. I used to be extremely shy (too shy to order my food at a restaurant and needed my mom to order it even when I was 17

). The interaction you get from social dancing has finally brought me out of my shell. I've seen someone who was even shyer than that start asking out women for the first time in his life after dancing (he is nearly 50 years old). I've seen people depressed for years from death/work problems/family issues finally emerge from depression after finding dancing. It is a safe way to get 2 minutes of attention from a stranger - and you don't even have to come up with an excuse or say a thing. Eventually enough of these small interactions and it really helps a lot of people.