The workers on the ranch represent the theme of tragic dreams; those that are never meant to come true. Those dreams were (are) a way to survive, a way to escape the realities of the Great Depression.
George’s claim that the dream, of running a farm and living off the fat of the land with Lennie, was nothing more than a calming mechanism was both saddening and all too real. Dreams are both fundamental (how do we accomplish anything as humans without an initial aspiration?) and doomed disappointment (how can reality ever live up to the fantasy we create?).
Ultimately, the lost dreams of those on the ranch enhance the emotional impact of the failure to make those dreams come true. Those who work on the farms are destined to be nothing but working hands during the week to earn the money they spend on women, gambling and alcohol on the weekends.