Disney paid a few billion dollars for the franchise and, thus far, it's been extremely profitable all around the world...except China.
Despite marketing the ever-loving $#!* out of The Force Awakens, the movie under-performed in China. So, when Rogue One was in its early stages, they rewrote the script to include two Chinese characters, whom they cast with two of China's biggest stars.
Again, Disney marketed the *%# out of Rogue One to the Chinese, and it did even worse than The Force Awakens had.
Why is this a problem? The Chinese market is taking up more and more of the global movie-going audience. If Star Wars isn't catching on in what will soon be the biggest market for movies, that's a very big problem for Disney if they want to wring every last dollar out of their sizable investment.
This will also have the side effect of making Lucasfilm more and more conservative about what the Star Wars brand is because, with the Chinese audience shrinking with each film, that means they'll have to maximize their returns from the rest of world by focusing on what has worked for them in the past, rather than experimenting with their successful formula.
Which may be part of the reason Lucasfilm would hire off-center filmmakers like Lord & Miller a few years ago, but suddenly start getting cold feet now, after the failure of both The Force Awakens and Rogue One in China, in addition to the consistent failure of Western comedies outside of English-speaking countries.