Star Wars movies aren’t building up to anything. It’s not an interconnected universe in the same way Marvel is (I mean it is, but not in the same way Marvel is chronological and has constant crossovers). And even with Marvel, there is a lot of leeway given to filmmakers in what stories are told, even if they affect later installments.
And there is a guiding hand, Kathleen Kennedy. She’s just decided she doesn’t want to hamper filmmakers with plans laid out by other filmmakers. Each film should stand on its own and tell its own story. It shouldn’t exist for the sole purpose of being a sequel or setting up a sequel. The level of success they’ve managed is up for debate but I don’t think there’s anything wrong with the methodology.