Why did they create the character of Ahsoka in the first place for the Clone Wars?
The sale of the Star Wars franchise and the courtship around that took a while. Contractually, there are "no go zones" unless Lucas approves. In effect, there is lots of fertile ground for storylines that can't get made without Lucas giving it a green light. For example, The Big Mouse can't just up and totally remake A New Hope next year.
In effect, if you were making Star Wars anything back in 2008, you had to keep one eye open for creating characters that would not be choked out in the future by potential legal complications.
A pretty classic case of this is Tom Clancy and the Jack Ryan character. Long ago, Clancy was in talks to buy the NFL's Minnesota Vikings. During hard vetting and discovery within that, it was evident that he was cheating on his wife. In the ensuing divorce proceedings, the "Jack Ryan" character became a legal point of dispute. The character was created during the actual timeline of the marriage. Thus Clancy created and expanded Rainbow Six. The Rainbow Six novel brought back John Clark and Ding Chavez as the main characters, and had a separate storyline in the Jack Ryan universe. This was back when Clancy stuff was red hot. And to stall more books, video games, concepts, films, etc, etc would be disastrous financially for lots of people involved. If you don't write about Jack Ryan at all, for a while, you don't have split half or more than half of the proceeds linked to Jack Ryan with your embattled future ex spouse.
I'm not a fan of The Big Mouse and Kathleen Kennedy and generally what's going on with Star Wars and it's current failures. But Lucas is not without accountability here too. IMHO, part of the distinction is that Lucas has great creative vision and he can make some great superficial spectacle ( I love the Holy Trilogy, I'm not taking that from him) but he's not some locked in infallible creative genius. Now Ralph McQuarrie, that guy was a pure all out non stop creative genius. Lawrence Kasdan and Brian DePalma, part of the original brain trust for the Holy Trilogy, those guys are in the range of what I'd call creative geniuses.
Lucas is a narcissist. And in the 70's, people and the culture were less suited to handle narcissists. It looks like being fearless to many people. In today's time, I don't think Lucas would have gotten as far as he did. Not just because everything is harder to do and costs more, but because in general, more people are more informed, and Lucas would just look like another industry grifter.
Maybe one of the saddest points in Star Wars fandom, that most people don't quite see at first, is when David Fincher's vision for a potential sequel trilogy was treated as non viable. Because there are legacy ties, Fincher would have gotten far more creative freedom than just about anyone else on tap back then. As the rumor goes, Fincher had a much more practical take on where the Star Wars legacy would go post Jedi ( i.e. the last functional narrative thread for conflict was Lando) Also many people wanted, very strongly, Jesse Plemons and Jessica Henwick to be the leads. We aren't talking Fat Todd from Breaking Bad version of Plemons, we are talking the version of Plemons that came from Peter Berg's Friday Night Lights. Most people here have seen Henwick in Iron Fist, and she is literally the best thing about it.
"Avatar" characters can be really dangerous for high level creatives. Hermoine Granger from the Harry Potter series is an avatar of JK Rowling. She's just a character approximation of how Rowling remembers and perceives her own childhood growing up. Hence Hermoine, in the books, gets into strange things like the Elf Liberation Front and gets dragged into tabloids as a "bad girl" who corrupts Harry Potter. For Shonda Rhimes, it's Dr Miranda Bailey in Greys Anatomy. For Chris Carter, it's the Cigarette Smoking Man ( and his failed writing career) in X Files. If you can balance out an avatar character, as a writer, it can be pretty useful.
So how this breaks down is Daisy Ridley/Rey is an avatar of Kathleen Kennedy. So, to point, someone like Kennedy, that level of malignant narcissism, can't envision her character version of herself being a mudblood like Henwick. Or kissing someone on screen like Plemons. I really enjoy Adam Driver as a performer, I think he's usually very good. Limited range but good. But he's not a great casting fit as Kylo Ren IMHO. But someone like Kennedy can see the young version of her character self kissing someone who looks like Adam Driver.
If Fincher cannot do his own casting, he's just not going to really play ball. So that was that. Can you imagine the kind of well rounded purposeful efficient storytelling we'd get from a pure David Fincher Sequel Trilogy. And the carefully curated visual aesthetics we'd get.
You'll say that there's no way that people can be this petty and this stupid, when this much money, power and legacy are at stake. But it's just people. Famous wealthy powerful connected people are just people too. They cheat, they have heartbreak, they fall in love, they cry, they need lots of real therapy, they have family problems, they get sick, they sink into cognitive dissonance, they self destruct. Think about every place you've ever worked in your life. And the quiet chaos that most outsiders never got to see but you might have seen every single day. Even look at this hobby sometimes. Not everyone but sometimes lots of people. Yes, people can really be that petty and stupid sometimes. But in this case, real legacy fans paid for it. People who grew up and loved all this.