This been my biggest gripe about so-called critics. This character development is the most OVERRATED critique to use. Character development only is important if it serves the plot and story overall. If this was a character study, then character development of course be important. Such as a movie like "Moonlight" which is a character study about a black man's conflict with his sexuality. Understanding the characters development that affect that premise would be important. But not for an ACTION WAR FILM. Rogue One is an action war film! It's premise isn't about CHARACTER, it is about accomplishing an near-impossible mission. It's about a band of rebels UNKNOWN to the Star Wars lore and were unsung heroes to what may orf been the turning point of the entire saga. We don't NEED to know their history and be all deep into their background and so forth. All we need to know is how they came together, and how they were able to accomplish the mission. Their personality and a small background was just enough. You still FELT them emotionally in what they were able to pull off.
Also, this thing about pacing. I can understand that on the 1st viewing it's a bit jagged... but I don't feel it at all being slow... you have to have to introduce these characters and set up the mission. It's why the 3RD ACT was so satisfying. It wouldn't be as good if it's been nothing but MICHAEL BAY fireworks and lack of story. Shoot, A New Hope 1st half of the film was boring AF.