Why did HAL sing Daisy in 2001: A Space Odyssey?

This is pretty amazing: It turns out that the song Daisy Bell which HAL sings in 2001: A Space Odyssey was based on one of the first songs that a computer was programmed to sing with a synthetic voice. It seems that Arthur C. Clarke was visiting Bell Labs back in the early 60s when he came across a demonstration of the new technology!