In some cases it's a good thing that people do not have their tattoos removed. An automatic system for matching and retrieving tattoos is said to help investigators and law enforcement to solve crimes. Law enforcement often times take photographs and note of people's tattoos and scar that can aid in identifying the criminal later in line-ups or with witnesses.
SPIE reported on the tattoo biometrics, "A wide variety of biometric systems have been developed for automatic recognition of individuals based on their anatomical (e.g., fingerprint, face, and iris) and behavioral (e.g., signature and gait) characteristics. Despite tremendous technological progress, there are many situations where primary biometric traits are either not available or are difficult to capture, or where the quality of the sensed images is poor. In such cases, 'soft' biometric traits such as height, sex, eye color, ethnicity, scars, marks, and tattoos can assist in identifying a person."
In some cases tattoos can be helpful tools and removal is in fact detrimental to such things.
