The real reason why Lou Grant was cancelled.
During the series run, Ed Asner was president of the Screen Actors Guild and Ed, who has many liberal views, publically spoke out against US involvement in El Salvador during a speech in 1982. I was in high school when he made this statement and I recall that almost immediately after he said that CBS announced that they were cancelling the series. Ostensibly, this was due to the series' low ratings but I have always suspected that it was because of his comments and that maybe politicians were worried that Ed would use this series to promote liberal views and maybe influence viewers. I don't normally subscribe to conspiracy theories but Politically Incorrect was cancelled in 2002 due to comments Bill Maher made about the 9/11 bombings and Susan Sarandon and Tim Robbins were not invited to the Baseball Hall of Fame in 2003 to celebrate the 25-year anniversary of the release of Bull Durham because they publically spoke out against the Iraqi Invasion so this may not necessarily be as far-fetched as it sounds.