When I read the book, I see the television screen walls as equivalent to modern day soap operas. The people sat home and immersed themselves in the lives of the "people" on the walls. Those pseudo-people become the be-all in the lives of the brain-dead people who sit and watch them all day. Montag often commented that his wife sometimes treated the walls as real people and real life while she disregarded him. The "walls" become more like family and real life than their real life does simply because their real life was so tasteless. Lack of books, controversy, issues to discuss--all of this results in a horribly boring life.
The TV family is called "family" because they actually serve that role in society. Each house is equipped with at least one TV wall, most have multiple walls in one room and the shows are actually interactive. The residents in the homes play parts in the family each day and albeit small parts the members of this society actually feel as if they are a part of these families. This is how the society operates, everything is simulated, even real family life. There are little to no actual emotions so that everyone can think that they are happy and content. Without real families there would not be any real fights or exchanges of emotion and therefore the society as a whole is easier to control.
The society is all united in which they think TV would be an absolute solution to everything