I think one of the lessons of Villeneuve's Dune is explicitly said at the end of Part 2: Sentimentality is weak. And it's bold I feel.
We can see that in the character of Jessica. Say what you want, but she is very sentimental... and very weak. She shivers, cry, barely holds herself together throughout the movies. And her defining trait is that she gave in to Leto for love and gave him a son rather than follow the Bene Geserit plan. But she changes when her unborn daughter get the Water of Life and starts talking to her. At this point, I'm starting to think she is manipulated by her even. What matters though is that she stops fretting and fearing, and becomes ruthlessly efficient.
We see it in Paul and Chani too. Paul is visibly upset about his destiny being laid out for him, and even more by it trampling on the Fremen, a people he does respect and want to integrate. Chani too is very emotional, she refuses the same idea Paul resists and she does fall in love with that man who do not want power in the name of morality. But at the end, it is for nothing. When Paul gains the Water of Life and sees the future clearly, he sees only one narrow path to military victory, and he rejects everything for it. Chani still loves Paul, but that love is consistently unable to stop anything, not Paul, not the worship of the Fremen for their messiah.
So often do work of fiction tell us that love wins over everything, and Dune does the opposite. Love, sentimentality, is a weak position to stand on. To rely on it makes you vulnerable, and easily swept away by cold pragmatism. Love is not efficient.
