I'd like to see those data combined with information about other social changes, specifically percentage of households where both spouses work, plus the prevalence of housekeepers. My subjective perception is that it's more common now for households to have two incomes, and more common in the past to have had a housekeeper to help with household chores. I'd like to know if there's any truth to that, since it would imply a huge reduction in the amount of leisure time in a typical household, even if individuals worked fewer hours per year than they used to.
Back on topic - many major sports have "easier" variants: baseball has softball, kickball, t-ball; (American) football has touch and flag versions; etc. We already have Frisbee golf - why not other variants to attract more casual players? If golf courses are seeing fewer people play, then it makes a certain amount of business sense.
Also, isn't this what a lot of casual players essentially do by taking a "mulligan"? A larger hole would basically be standardizing the "mulligan distance."