No, the main problem with the sequels is that they add nothing to the lore. The first 2 books have a very detailed description of Dune universe and Arrakis and

No, the main problem with the sequels is that they add nothing to the lore. The first 2 books have a very detailed description of Dune universe and Arrakis and all the political factions. The rest of the saga brings nothing new or really interesting. They feel derivative. Nothing in the sequels have not been said in the first 2 books. So they felt already uninspired. It gets even worse after God Emperor of Dune, Herbert clearly had nothing more tosay after that. Dune isn't a "geek power fantasy" Isekai style, it's a cautionary tale against blind faith in leaders and religion. It's made clear from the start that the protagonist, Paul, isn't a hero, as him and his mother manipulate the fremens to gain their trust.