Women have been entering the fields of mathematics, engineering, and science more and more in recent years. While more have entered computer science as well, there are far fewer than in the other fields. Not only are there fewer, but the rate of increase has dropped, while other fields' rates continue to rise. Women are needed in computer science because they think differently than men do---not better or worse---but differently.
Innovation springs from creativity, and creativity is nourished by exposure to a breadth of ideas and viewpoints. Pixar strongly believes in this aspect of creativity, and has carefully designed its offices, culture, and production process to make sure everyone interacts with as many people as possible. They have shown that it works. A limited pool of viewpoints with collaboration restricted to a handful of people is not healthy for creative thinking, and will be stagnant compared to what we can achieve with more varied minds. We need more women, more artists, more people with different training and backgrounds to add spice to the industry.