I believe that all of the above posts make valid points for discussion but believe that demands upon their free time is a big reason for not camping. Children today (and grandchildren), are enrolled in so many activities that demand parents (and grandparents) time that little is left for themselves. I see parents shuttling their kids off to sports practices and games at all hours and days all in the name of good parenting.
I golf quite a bit in the summer months and have observed that each year the "head count" of golfers goes down and a few more golf courses are torn up and returned to farm ground. Surveys by people in that industry reveal that "lack of free time" is the leading reason given by prospective golfers. I don't believe that there is less free time today, it's just spent being more responsive to the children's demands.