I agree with the need for an empirical reality check, but have grown really skeptical about these kinds of cohort-level well-being measures.
I wouldn't say they're meaningless, but there's a lot of studies suggesting they don't really change much over time, and my sense is they don't change in tandem with events that should change well-being, except in extremes like widespread genocidal war.
There's even researchers who have kind of taken them seriously to suggest that people have social cognitive biases about the past, and societal changes. I respect them and think what they're suggesting is reasonable (in the sense that they're taking the measures seriously) but the other way of looking at it is to flip it around and raise the possibility that the aggregation-level measurement isn't tracking what we want it to.
I admit I don't have an alternative, and don't think they're worthless per se, I just feel like (as someone who does vaguely related research) like they're tracking something more akin to perceptual sets or world schemas than psychosocial functioning.
I guess at some level I always have the "everything is fine" dog meme in the back of my mind when I see these kinds of well-being or mood analyses.