Why does Bradbury include the exact times of specific events in "There Will Come Soft Rains"?

The chronology is important in this story because it creates suspense and helps the reader understand the effect of no longer having humans.
Is time important when there are no longer people around to perceive it?  That is one of the philosophical questions that Bradbury wants us to ponder with “There Will Come Soft Rains.”  The people are dead, and the house continues on.  Its robots still function, regulated by the time-oriented society that humans created.

Eight-one, tick-tock, eight-one o'clock, off to school, off to work, run, run, eight-one! But no doors slammed, no carpets took the soft tread of rubber heels.  It was raining outside. The weather box on the front door sang quietly: "Rain, rain, go away; rubbers, raincoats for today…” 

The ticking off of the time increases suspense because as the automated house goes through the motions even as its clear that the people are only spots of paint, the reader knows that the clock is moving toward something.  We do not know what until the fire starts. 

At ten o'clock the house began to die.
The wind blew. A falling tree bough crashed through the kitchen window. Cleaning solvent,bottled, shattered over the stove. The room was ablaze in an instant!
"Fire!" screamed a voice. The house lights flashed, water pumps shot water from the ceilings. … 

The countdown to the fire is even more tragic because of the fact that the automated house is counting off time for people who do not exist.  It is continuing to make breakfast and call out announcements, but it does not acknowledge that the people are long gone.  The reader knows that something is going to happen, and the fire is that something.
Humans are emotional creatures.  Appliances and robots are not.  In this story, the personification of the house and its automaton inhabitants as the clock ticks creates suspense that makes the reader ponder his own mortality as the residents of the house get closer to theirs.