Why did Ray Bradbury title his story "There Will Come Soft Rains?"

To see why Bradbury gave his story this title, just look
at the poem by Sara Teasdale that the house recites before the fire
starts.

In this poem, Teasdale is saying that nature will
not care at all if human beings cease to exist.  If people vanish, the Earth and all the
other creatures would continue to exist and would probably do so quite
happily.

In this story, Bradbury is showing us how our
technology is starting to make this a real possibility.  He is saying that we are
gaining the power to wipe ourselves off the face of the Earth.  If we do, however, we
will find (actually we won't because we won't exist) that we are not really that
important -- life on Earth will continue without us if we are so stupid as to make
ourselves extinct.