I appreciated the change to make Chani fill a role like Sherif Ali in the film
Lawrence Of Arabia (the book
Seven Pillars of Wisdom, if not the film, is plainly a huge influence on Herbert's
Dune, and it's probably impossible for a director to film so much as a scene set in the desert without thinking of Lean's film).
So much of Dune takes place inside people's heads that it's basically unfilmable if you don't make some changes. Plus, even with five hours of film, you're going to be cutting whole scenes from the book whether you want to or not. Lynch's solution was to make it a more straightforward hero's journey—and given the length of his film, and no expectation of sequels, I can't really blame him. Villeneuve had more space and so could tell a darker and more foreboding story, closer to the original, but still needed to externalize some of that internal struggle and foreshadowing, for which he used, especially, Chani.
[EDIT] Oh and as for this:
> I know its nerdy but I absolutely hate when movies of classic books think the story needs to be changed
Every now and then such a deviation ends up being excellent as its own way, while still benefitting from the connection to the original and being better as an "adaptation" than an independent property. Verhoeven's Starship Troopers would be one of the more extreme examples of this kind of outcome. A gentler one might be Kubrick's The Shining.