What you’re asking is the implied question. Is the shift due to changing demographics? Or is it evidence of malnutrition, that city kids are not reaching their genetic optima?
At a population level, ceteris paribus and longitudinally, height is a health indicator. Individually or comparatively it’s useless.
If we see a clear health disparity between two groups who should otherwise have equal outcomes, then it implies there’s possibly something in the environment of one group that’s negatively effecting them. And therefore could possibly have other side effects we’re not privy too.
You say height is of no importance, but a majority of women[0][1] would disagree, and men below average height would also disagree. Perhaps our evolutionary signals point to something other than “a social construct” for choosing height in mates. Wild thought.
0 - https://www.sciencedirect.com/science/article/abs/pii/S01918...
1 - https://www.wsj.com/articles/online-dating-investing-match-t... (quote of note: “A former Bumble product manager says that a majority of women on the platform tend to set a floor of 6 feet for men, which would limit their candidate pool to about 15% of the population.“)
They physical advantages of height are very apparent and simple to understand. Even animals recognize the larger you are the safer you are (generally). How is that inconsequential?
In fact I would argue having an arms race for ever bigger humans is antisocial and detrimental... just the carbon footprint aspects alone is a good reason to discourage that. The extra stress on our food system. Bigger cars, airplanes, fuel, etc... as opposed to women dig it and you can beat people up. Really?
An individual person’s height isn’t an indicator of health but in aggregate the statistics matter.
I don’t see the analogy with race working in this context.