I recently came across some dresses that reminded me of the musical You're a Good Man, Charlie Brown, a musical based on the cartoons of Charles M. Schulz. The show premiered in 1967. Which would account for the drop waist dresses in the show. It looks more realistic to me when you use period sewing patterns rather then a costume sewing pattern. Even if the period is the 1960s.
Lucy is the height of 1960's fashion in a drop waist dress
So is Sally Brown
These are the dresses that reminded me of the cartoons and the musical.
This is a costume pattern inspired by the comic.