I don’t know why some people in online discussions think assertions of counterfactual history—which by definition no one can either prove or refute—constitute valid moral arguments.
“Hawaii would have been conquered by Japan eventually anyway”
You can’t prove that, and so what? The republican coup and US annexation were still wrong.
It is reasonable on the other hand to argue that the abolition of the German and Austro-Hungarian monarchies in 1918 paved the way for the rise of Nazism and the subsequent expansion of Communism. This can be demonstrated with facts and logic. Had the monarchies survived, their peoples might have been spared a great deal of suffering. But counterfactual scenarios, however enticing (and no one wishes 20th century European history had proceeded differently more than me), are not the core of the moral argument.
I believe that the abolition of an ancient monarchy, let alone dozens of them at once, is wrong in itself, regardless of consequences. It is an offence against obedience, tradition, patriotism, aesthetics, the foundation of all previous legality, and the divine order. And that is why restoration is a moral imperative even after the most obvious negative consequences have subsided. Modern Germany and Austria, and the other lands that once made up the Habsburg Empire, may be decent places to live in a narrow materialistic sense, though it took over three decades in the West and seven in the East after the falls of the monarchies for that to be the case, with unprecedented horrors along the way. But there is more to life than materialism.
We cannot bring the dead back to life. But when something wrong was done, no matter how long ago, that can be reversed, it must be. And that is why I will insist as long as I draw breath that the occupation of Germany, Austria, Hawaii, and other countries that used to be monarchies by republican regimes is intrinsically immoral, because it constitutes an injustice that though it could be has never been corrected.