In "There Will Come Soft Rains," why do you think Bradbury chose to have the house broadcast the poem?

Bradbury takes his poem about the end of humanity on earth from the poet Sara Teasdale.  Teasdale's poem considers the relatively small impact humans have had on Earth despite their brutuality towards one another.  Penned in 1920, the poet was writing in the wake of the atrocities of World War I, the "War to End All Wars."  That war saw horrors like mustard gas, a first in the race of mankind to exterminate itself.  Little did Teasdale know how much worse things could get.

Bradbury wrote his short story in 1951, in the aftermath of World War II.  Though much of humanity had survived nuclear war, Bradbury too wondered how much longer humanity could survive given its penchant for destruction.  Here is the text of Teasdale's poem:

There will come soft rains and the smell of the ground,
And swallows circling with their shimmering sound;
And frogs in the pool singing at night,
And wild plum trees in tremulous white;
Robins will wear their feathery fire,
Whistling their whims on a low fence-wire;
And not one will know of the war, not one
Will care at last when it is done.
Not one would mind, neither bird nor tree,
If mankind perished utterly;
And Spring herself when she woke at dawn
Would scarcely know that we were gone.

As the house continues on its scheduled pace, and its occupants have been reduced to smears on the walls, Bradbury asks if nature has found a way to do without what seems to be a failed experiment.   The poem seemed to capture his question.