Google+ makes connecting with people on the web more like connecting with people in the real world. It's recommended that you go by your first and last name because it will help you connect with people you know and help them find you.
This policy applies only to Google+ profiles. Google+ profiles are for individuals. If you want to use Google+ to represent someone or something other than yourself -- like your business, your band, your family, or your pet -- you should create a Google+ page instead.