We thought people would like them.

About Laurie Anderson - The End of the Moon:
Near the beginning of her show, she described a conversation with the NASA official who chose the pink-and-blue color scheme for the Hubble photographs of the universe. (Some of the tints picked up by instruments could not be seen by the human eye.)
When she asked him how he had chosen those colors, he innocently said, "We thought people would like them."

http://www.nytimes.com/2004/11/11/arts/design/11moon.html