I think what's being ground up against here is that weapon proficiencies tied to race inherently don't make sense in most cases, so arguing lore justifications are going to work.
In the case of Battleaxes, Handaxes, Light Hammers, and Warhammers for Dwarves and the Militant Githyanki with Longswords and 2-handed swords I feel like those do make sense culturally.
However, adding humans to that mix does not make a whole lot of sense. It would seem to reduce humanity to a monoculture despite there being a lot of different races of humans with a lot of different backgrounds.
I'll admit, I am not in agreement with the human changes. I am at a bit of a loss given how strongly the community requested Variant Human - and that would have been popular with the community, new players, old players, Santa clause, most of The Beatles, the New York Giants and left-handed proctologists.
Well, hopefully it gets changed or we mod it out.