Tribal tattoos have been been practiced in one form or another for millenia. While the practice may be somewhat different nowadays there are still many who get tribal tattoos for reasons which could be described as neo-tribal in their quest to belong to a 'tribe' (either neo-tribal or traditional) even if it is on a subconscious level. Most simply get tribal tattoos because of their striking appearance.
Historically getting tattooed was seen as a rite of passage into adulthood. A belief goes that if a girl can't take the pain of tattooing, she is un-marriageable, because she will never be able to deal with the pain of child birth. If a boy can't deal with the pain he is considered to be a bad risk as a warrior, and could become isolated from the tribe.