What? Dude. Way to miss the entire message of Dune. It's a critique of imperialism. Paul is not the hero. Paul taking the mantle of Lisan Al-Gaib is not a good thing. Him becoming the emperor is not a "fuck yeah white people" moment, it's sad, because the idealist has become part of the system of oppression he used to be against.

The movie is a critique of white supremacy as well. Given the changes they make to Chani where she is a lot more vocal in her issues with Paul waltzing in and leading the Fremen when he doesn't come from their culture. And her anger when he actually takes on the mantle of Lisan Al-Gaib (which he initially did not want to do). And at the end where she leaves in disgust as Paul ascends to the throne.

Also Paul does not actually "ditch his Fremen girlfriend and take up with a white girl", in the books he is only husband to Irulan in name and not in any other way. He keeps Chani as his lover and consort, and only ever has sex with her. Chani is constantly with him in Dune: Messiah.

In the movie I think they made Paul choosing Irulan more ambiguous in order to actually make Chani the viewpoint from which the audience is made even more clear that his actions at the end of Dune are NOT heroic. That him taking power is not a cheer worthy moment, but a fall.

Which is the overall message of the story, but I think Denis Villaneuve made it clearer for Dune 2 because a lot of readers misinterpreted the first Dune book before Frank Herbert wrote Dune Messiah.