Oh, MFI! God, that's a blast from the past. I'd forgotten all about them.
It just seems that many people back then had 9-5 jobs, a family house on one salary, job security - you stayed at one place for forty years and then got a gold watch on retirement - and work did not bleed into evenings and weekends.
I haven't thought about it in as much depth as you suggest; they're just feelings I've had as I watched the older generations in my family, and this thread is for things you wouldn't admit out loud, so...
All four of my grandparents had retirements of quarter of a century, but they did live through two world wars and came from dreadful poverty. They also didn't indulge themselves with endless travel. Their children, my late parents and my aunts and uncles, didn't have such long retirements but went on truly endless long holidays for YEARS. I could never do that. I'm British but moved to the US in my early thirties for lurve, so have been there for many years now, and I do think the sheer number of holidays the British take is a disgrace. That's any age, not just retirement. British people, it seems to me, just don't want to work, whether that's taking early retirement while in great health and travelling all the time, or taking as many holiday as possible at any age. It's probably why our output is so low compared to other countries. We are lazy, that's what it comes down to.