Making a realistic and lifelike human character is one of the hardest tasks in 3D graphics. For a long time it was known as the 'Holy Grail' among 3D artists in the community. The reason why this skill is so desired, is the possibilities it gives you in the movie or advertising industries.
Imagine you could create fully artificial digital actors and make the audience believe they are real. So real that there would be no questioning it. We are all familiar with the best examples out there - Gollum in the Lord of the Rings Trilogy, Davy Jones in the Pirates of the Caribbean or the alien species in Avatar.