So why not just make it animated and call it Rebels Season 5?
Making it live action implies that it’s a continuation of the current live action shows like Mando Season 2 where Ashoka showed up previously. It’s totally understandable why average viewers are confused that they have to watch an animated kids show set before the Galactic Civil War to understand what’s happening in a presumably adult-oriented post-Galactic Civil War show.
In all honestly, it likely should have been animated. But since they want Thrawn as the big bad of the Mandoverse, and they painted themselves into a corner with the ending of Rebels, what other choice did they have?