Well, from the story, it appears that the father wants his son to come home, though never really knowing if it would happen, yet he still looks out past the village hoping to see him each day.
When the son comes home, the father runs (an act of potential dishonor from the towns folk), grabs his son, hugs him, brings him back to his land, gives him a ring, and throws a party for the son. Not much is said about what happens after this event, other than the other son becoming angry that the father would do this. I wonder who, in the story, the "other son" would be?
Anyway, it seems obvious that the father's joy was not in "having another worker for the lands", he had his other son, and hired hands (I also wonder who the hired hands represent). So, the father's joy came from his son being back home.
The story has always been told from the aspect of the son, . . . .but I think it is of equal (if not greater) importance to see the actions of the father.