Bryan Colley at 2012-04-20 16:13:07:
There were sequels in 1982, but they won't show up on anyone's list of fond memories. Sequels in the 80s were crap - made on the cheap and often with different actors and creative teams.
Sequels as Hollywood's cash cow happened in the 90s after corporations took over and marketing depts. started calling the shots. Marketing figured the easiest thing to sell to the public was a sequel to a hit film. The hardest thing to sell was an original drama. Hollywood went for the easy sell.