TwoSix
Everyone's literal second-favorite poster
The problem here is that "meaningfully different" is doing an awful lot of work. How many features, and what level of strength of those features, is required before the distinctions become "meaningful"?If a dwarf isn't meaningfully different from a human, and doesn't have anything strongly culturally understood as dwarfish, the choice between one or the other becomes basically a choice of superpower, and hey I like Legion of Superheroes, but not on my D&D.
And to the cultural point, I think we're all aware at this point that the core PHB isn't meant to be culturally specific. Dwarves and elves are all culturally distinct for every published setting, and the core rules are simply meant to evoke the core concepts of the race, the absolute bare minimum to suggest the race's most commonly agreed upon tropes.