Why date?

Young men and young women, you need each other. You really can make a difference by helping each other stay active in the Church and live by its standards.

Young men and women will be better prepared to meet life's obligations and create happy, healthy families of their own if they will:
Show proper respect for each other.
Learn how to socialize in appropriate, mixed-group activities.
Do more than just getting together without doing anything planned.
Learn how to date properly and then do so.

Making new friends. Being in mixed company outside a classroom setting can be a great way to make new friends in a nondating environment. UAdd a Note

Helping each other live gospel standards. You can help each other stay strong and make good decisions. For example, some teens gathered to watch a video. Someone suggested they watch a video that didn’t meet gospel standards. When a few in the group quickly protested, the group decided to watch a more appropriate video instead. Some in that group may not have been willing to speak out against the first video. But after watching the example of others, maybe next time they will be the ones speaking up, or even suggesting more wholesome movies in the first place. UAdd a Note

Learning social skills. Getting together as friends can be a great setting for learning how to socialize properly. Some youth feel comfortable talking and socializing with members of the opposite sex. But others feel very nervous and awkward. This is not unusual. Those who are less comfortable can learn from those who are more comfortable. The examples of those who are comfortable can help make it easier for those less comfortable.

http://new.lds.org/new-era/1992/03/fyi-for-your-information?lang=eng
http://new.lds.org/new-era/2005/09/qa-questions-and-answers?lang=eng
http://new.lds.org/new-era/2006/08/why-date?lang=eng