And there's plenty of precedent in real life, too. Before WWII, anti-Semitism and bigotry against immigrants were rampant in the United States, and a lot of Americans were sympathetic to the Nazis. But once the world learned of the atrocities of the Holocaust -- once they were brought out into the open -- it changed things, discrediting such hate groups and beginning the modern push toward increased acceptance and equality.
I agree with the overarching thrust of your argument, Christopher, but this example is extremely flawed. If you're claiming that bigotry against immigrants is any less today, just look to Arizona and Sheriff Arpaio, or to the tremendous pushback against any attempts at granting amnesty. (Arpaio, by the way, is a great counterexample to the idea that openness can reduce
bigotry; he isn't working in secret by any means whatsoever. He's in fact
proud of what he's doing, and never ceases to broadcast it. Openness can prevent the misuse of technology, but it can't prevent
all negative events just by virtue of itself.)
It's not that anti-immigrant feelings were reduced, they were just redirected from Jewish immigrants to the next immigration wave. Exactly what happened with the Italian immigration wave, the Irish immigration wave, the German and Polish immigration wave, and the Chinese immigration wave. It's not acknowledgement of atrocities that caused bigotry to lessen, but the assimilation of the culture over time; each culture assimilated and was no longer seen as an other, and then the next immigration wave brought a whole new other for people to fear. The same thing will probably happen to the current Hispanic immigration wave given enough time, but this entire topic is a complete non sequitor when it comes to the effects of openness on public policy.
(Note that I'm not saying that acknowledgement of the Holocaust wasn't a major factor in reducing explicit anti-Semitic feelings, but rather that it wasn't a major factor specifically in the changing opinion of the Jewish immigration wave over time; that
that opinion simply evolved over time the same way it had evolved for every immigration wave before or since.)