Being Nice???

I went out with some friends the other night. We went to a bar downtown that I had never been to. It was a great place for people watching. In the bar, there were people of a wide variety of ages and races, all hanging out, yelling at each other over the music, and dancing together, generally having a good time. I found the interactions between the men and the women in the bar particularly interesting. We met a group of guys and were chatting with them a bit. They moved on and were dancing with some of the women in the bar. One of the guys was dancing for a long time with a girl there. Before the bar closed, and everyone left, the guy took the girl's phone number, put it in his cell phone, and said to the girl something to the effect of "Talk to you soon." The girl left and we were standing talking to the guy as we were walking out. We questioned him about whether he would really call the girl he had been dancing with. He said no. So we asked him why he bothered taking her phone number. He said that he did it to be nice. That made me wonder about whether this action was nice or not. I guess it made the girl feel good that he liked her enough to press the few buttons it took to put her number into his cell phone. But how nice is it when the girl is waiting around for him to make a phone call he obviously has absolutely no intention of making? Would it have been nicer for the guy to be honest and tell her that he had fun dancing with her and leave it at that? Maybe she would have been disappointed that he didn't ask for her number after an hour of dancing, but she surely wouldn't have the expectation or the anticipation for days afterwards of waiting for the phone call. I am sure that most women in this situation know that there is only a slight possibility of the guy actually calling them. I think if I was in that world on a regular basis, I would have learned by now that dancing with someone in bar led to an extremely slim possibility of an actual relationship. I imagine that it is not a complete surprise when no call actually results from that interaction. But I still wonder why a guy would think it is being nice to take a number when he has no intention of calling it. Anyone want to explain?