Certain events require by the special dress code to wear only opera gloves. Now, you know what leangth they mean. Also it should only be made of kid-lambskin leather. Some gala evenings, grand balls, performances and other grandious events might require that specific attire and accessory.
Styles have been changing throughout the time, but some traditions remain constant.
For example ties the debutante ball in England and modern day American debutante, all of them suppose to be wearing of above-the-elbow (or opera) white kidskin leather debutante gloves. Those Debutante Gloves has been recognized for over a century as one of the foremost symbols of upper-class femininity.
Don't hesitate and afraid to be feminine and classy. Those are the things that will never go out of style.