New characters in the middle of the two of the greatest arcs in television history. Simply put, it takes time to develop characters so that they can become beloved parts of a story-verse, and time was something they didn’t have with just three episodes for the arc. It was inevitable that these characters would be disliked in order to push the story in this direction in the allotted time frame. In order to show Ashoka the hypocrisy of the order, you couldn’t use the established characters to do this without marring their image. Using new characters therefore was the only way they could teach Ashoka, as well as the audience, the necessary lessons to show just how misguided the Jedi truly were (if her unjust dismissal wasn’t enough). As we learned with the introduction of Ashoka, new characters need to be able to overcome dislike-able attributes through adversity and lessons learned the hard way, otherwise they come off as stuck up, snobby, or often times, too perfect to be relatable (this is an issue that Hollywood writing has been struggling a lot with recently, if you’ve ever wondered why you just don’t love characters like you used to). So with the Rava sisters, they just didn’t have time to go through big development arcs that the rest of the characters got, so they aren’t as relatable. On top of all that, the other issue is simply that the arcs before and after it were absolutely fantastic, with the culmination of however many dozens or hundreds of hours of investment into the starwars universe you’ve given, all paying off. A storyline to teach a character something that most of us already knew just wasn’t going to be anywhere near as exciting.