Its worth noting that most of these examples are for more episodic film series. They reference past events and character interactions, and tease future installments, but generally the plots of most of these films are more self-contained. There's usually a single predicament and a new revolving bad guy, and things generally get resolved by the end. Returning things to a kind of status quo. These kinds of movies generally have more leeway to wing it from film to film.
This is different than the PT and ST, which are clearly structured to go together like a 3 act play/epic trilogy. This isnt really the kind of project that's easy to make up as you go along. Cause if you decide you don't like how the narrative is going, you have little time to change it with the freight train of production scheduling for the finale coming behind you.
Again, there are plenty of trilogies that weren't planned out but were successful - having a master plan is not a pre-requisite for success. Even if we start making entirely arbitrary distinctions and say "Okay
this is just a loosely connected series of films while
this is a Real Trilogy" that still doesn't change the fact that the Mission Impossible films manage to build on prior entires and deliver satisfying conclusions with each installment, or that the modern Planet of the Apes films managed to produce three pretty great films that build on each other. Yes, Matt Reeves wrote and directed the last two films, but there was zero guarantee that Dawn would produce a sequel, so he basically left everything on the field.
Repeatedly hammering the idea that the ST "failed" because it wasn't planned out is such empty criticism because there's literally zero evidence that having a master plan is an objectively good thing. You can go on and on about how Star Wars is
really a three act structure and thus requires some kind of plan but there's nothing supporting that argument besides the "it just makes sense" gut feel.
This is all especially silly in light of the fact that Trevorrow's aborted film - we can
literally read the script and see what a (badly executed) good faith attempt to follow up on TLJ looks like and it reads a lot more satisfying that TROS.
*EDIT* And like...the ST clearly
did have a pre-planned destination - it was Leia (with Rey's help) redeeming Kylo, with each film exploring Kylo's relationship with one of the three heroes of the OT (Han in TFA, Luke in TLJ, and Leia in IX). This was glaringly obvious the minute the credits rolled on TFA, and prior to Fisher's death this was being repeated up and down by almost everyone involved.
It's just that, you know, Fisher died right before TLJ was released and it left everyone scrambling.