The show "All in the Family" was significant because it was one of the first TV shows to pay a great deal of attention to the major social issues that were relevant to American society in the 1970s.
The 1970s was a time when US society was having to deal with the impact of the changes of the 1960s. Society was changing, but there were many in society who were not at all happy with those changes. This was playing out all over America and it was encapsulated in this show. The show portrayed Archie Bunker's problems with the changes that were going on in areas such as race relations and sexual values. The show was important because it helped Americans to confront and deal with the fact that their society was undergoing important changes.