Your side note implies this would be a bad or nefarious thing? What if it's actually a good decision for both individuals and the public at large?

The issue is using a single factor to push change does not mean that change is a net good. Nobody talks about windmills killing birds because that’s what they actually care about, instead there are so few downsides they needed to find something no matter how meaningless in context.

As such single issues are often a fake justification for what they want to happen for other reasons.

I doubt it would be a good decision for all individuals. Maybe the public at large, but I question if that would be what motivates the people who seek such changes the most.

I mean, it could be both good and bad depending on the person. My Dad worked physically demanding jobs, and would have been happy to retire and spend his time working on personal projects at age 60, and his health and well-being would have been better if he had not had to keep doing exhausting work for at least 8 more years for money reasons. So, I think people feel justifiably protective of our elders when people talk about raising the retirement age.

Honestly, the jobs where the benefits of stimulation and social interaction outweigh the physical and or mental stress of the job are not the kind of jobs most people have. So if you wanted to do what’s really best for most older people, it would be better to find ways to engage them other than financially forcing them to keep working whatever job they can get - which is what raising retirement age does.

What would be really killer would be finding more ways to enlist retirement-age professionals in training young people, in a variety of occupations from carpentry to programming. The young have the stamina and strength but lack wisdom; the older people have learned a lot and could share that knowledge and wisdom.

"Good for both individuals and the public at large" is one thing. "We found a club to beat you into doing what we want you to" looks very similar, but is quite different in how it feels and how it works out.

What’s so difficult to understand? The state or lobbying groups want to raise the retirement age which then correlates with studies on how raising the retirement age has “good effects”.[1] The goal isn’t to find out what is good for senior people. It’s to find reasons to enact the policy that they wanted.

Surprisingly, men ages 51–64 (this was specifically about men) “need” their jobs for their own health.

We could imagine studies done in more patriarchal cultures: unmarried women over the age of 40 suffer from psychological and physical health problems more than married women over the age of 40. We’ll just leave out the parts about how unmarried women are penalized socially, constantly. Policy recommendation: we should get women married, it’s just good for them.

[1] This was the hypothetical laid out in the original comment.