Because these people were forced by their government to go to war, they're trash and losers? Disgusting.
That is an irrelevance. Only the strategic motivations of war matter which judging the war as a whole.
To focus on soldiers or if they "have a choice" is no different from, say, Clean Wehrmacht bullshit. You can judge the actions of soldiers, of course, but that does not justify
the war.
If you wish to discuss this in a serious way, then the answer is that the US ended up on "the right side" of WWII by part happenstance, part policy inertia in favor of the UK, and part desire to take over the world. That this desire to take over the world was under the framework of liberalism and economic extraction rather than fascism and racial extermination is hardly much of a moral high ground for the US.
Had the UK signed armistice with Germany and Japan's generals not been so paranoid as to go for a preemptive decapitation strike, then in all likelihood the US wouldn't have been a participant in WWII at all.
The US did not enter WWII to stop the holocaust. At most you could say that the US happened to stop the holocaust earlier on than it would have if they'd stayed neutral and the USSR marched to the shores of France. To give the US moral credit for stopping the holocaust and thus say the US was good in WWII is ex post facto and a poor understanding of geopolitics at best.