I'm not sure the rules have changed, but I think kicking has become much more specialized since then. Somewhere back around then, field goals were usually a drop-kick rather than place kick, which is much more difficult. The QB was often the kicker. I'm not sure when that changed, by the time I started following football in the early 70's, drop kicks were a thing of the past.
I assume the goal post was on the goal line then, which should have made it easier in theory.
Is it possible they were reluctant to kick because of an injury? Otherwise, I suspect teams have just gotten much more efficient at kicking in the last 60-70 years.
These are mostly assumptions, I'll be interested if someone actually remembers any differences.