Therefore if you include mechanics relating only to the injustices committed in democratic countries you run the risk of modelling a rather absurd world where only the democratic nations are shown to be internally repressive, which seems somewhat twisted.
I completely understand your concern, I have heard many stories about how many multiplayer games are awash with anti-Semitic jokes, and Paradox wants to avoid another
Six Days in Fallujah style controversy. But for now apparently HOI4 does not have the courage to show what
Call of Duty: World at War could, or heck, the
Valkyria Chronicles 
I'm not saying I certain numbered unit outside of Harbin, or the events discussed at a certain conference by a Berlin lake, have to be included. But genocide and discrimination are not quite the same. Look, the fact is that HOI4 already includes exactly the kind of discrimination we are talking about:
And of course the poster child for racial discrimination represented in HOI4:
That is A LOT of ethnic+racial and religious discrimination represented in the game
ALREADY. These are the very kind of game mechanics that would be relevant to the USA.
Some people thing this is awful, I think it makes the game better.
As far as the imbalance goes, that is a different story - I actually agree with you: Lets face it, Nazi Germany should probably have a modifier about their ideological recruitment policy, as while they took over some 35 million Poles after 1939, some in German core territory,' astonishingly few if any were actually recruited for any military or paramilitary purpose. Arguably, that is also an element with the Japanese military with Koreans and Formosans, although it is a bit more complicated there. Either way, there is room for improvement and further discussion.
If you choose to fully embrace segregaationism you will receive a hefty bonus of indutrial effience at the cost of man power
An interesting idea, I like your other points
, but I think we should take a look at Roosevelt's
Executive Order 8802, and this quote directly:
"There is evidence available that needed workers have been barred from industries engaged in defense production solely because of considerations of race, creed, color or national origin, to the detriment of workers' morale and of national unity."
According to Paula
Pfeffer in A. Philip Randolph, Pioneer of the Civil Rights Movement in the lead up to the war as the defence industry in the US exploded, it was white Americans who benefited: blacks- even skilled workers with proper training - were denied employment opportunities and access to government training programs. Well... aside from janitor positions...
So if anything, the only benefit for keeping things as they are is to keep a lid on the so called 'Dixiecrats,' but even then you risk civil upheaval: Executive Order 8802 only got signed because by 1941 the
March on Washington Movement (MOWM) had formed and 50,000 to 100,000 black Americans were ready to take a stroll up to capitol hill - and that was strictly without Communist support.
It is remarkable for an outsider to look on that period and see just how tense and volatile that period was in American social history. I know some are reluctant because of current 'tensions,' but a wealth of alternate history and interwar dynamic politics game-play are lost if such history is deliberately obscured.
