Why does Steinback describe the actions of Lennies hands?

Hands are shown to be a major motif in Of Mice and Men.One of the major themes of this novella is that often man brings about his own downfall. Hands often show a broken dream.

Lennie's hands kill everything he touches.

Curley's hand that he uses to please his wife is broken by Lennie.

Curley's hands (which are used for boxing) cause him to get into fights and get hurt.

Candy is missing a hand, which makes him less effective on the ranch and leads him to suspect he will soon be out of a job.

George's hands kill Lennie, which means he will never have his own ranch.

Curley's wife's hands could have been used for gesticulation in Hollywood, but she never gets the chance.