Despite loving the movie I still can't get over how bad the first act is and the lack of proper character building. The fact that I walked out of the movie and could only name about half of the Rogue One team speaks volumes. For instance, what exactly was Cargo Pilot's arc? I thought it was really dumb that his reasons for defecting happen off-screen before the movie begins, as such his character has no place to go once they find him. What's even more confusing, and likely a product of the reshoots, is the way his character acts in those brief moments before his mind is fucked with. He's super neurotic and flinchy with a bit of snark, however, the next time we see him he's completely emotionless and stays that way for much of the film.
The super odd thing is that he doesn't do anything that relates to his prior occupation. You see when you are building this type of suicide squad you need a small team of experts (demolitions, heavy ordinance/tank, pilot, spy, technical expert, etc.) but the Rogue One team is really haphazard and doesn't use it's characters appropriately. Why didn't cargo pilot do any actual piloting? When they leave Jedha and the planet is crumbling all around them requiring some expert piloting skill why isn't he the one piloting the ship? When they try to fly sneakily into Edou he gives directions since he's been there before and tells Cassian to fly dangerously low, again why isn't he just piloting? And, then at the last act he merely pilots the ship into Sariff base but then spends the rest of the fight on the ground handling communications, why? Why not, I don't know do some piloting shit (maybe he was the guy in the cut TIE fighter)?
Blind guy is a mystic/sage but doesn't really use his mysticism except to flip a switch. Yes, technically Obi-Wan did the same but he was also mentoring Luke in the ways of The Force, coming up with plans like disguising as Imperials, and fought Vader. Donnie Yen doesn't really do much old man sage mentoring, instead he basically gets slotted as DPS to clean up after Machine Gun guy's Tank agro. Cassian's problem is that he does too much, he should just be doing spy shit, basically infiltrating shit and assassinating folks. But, he's also piloting shit, coming up with all the plans, leading shit, and even gets to kill the main baddie. Some of his responsibilities needed to be handed over to Jyn, in the last act it should have been clear she was in charge and doling out all the responsibilities of the crew not relegated to giving speeches and grabbing beta disks.
However, back to the pilot because he's an example of just really untapped potential. There is nothing behind his character besides what you get at face value, which is true of most of the characters. None of them have any real shocking twists. In GotG the twist about the cast is that they are all "losers," who nobody takes seriously. By recognizing this fact they are able to altogether use their unique skills to outwit their enemies and take down the baddie. Thus, what if cargo pilot guy was a coward who lied about his reasons for defecting? What if he was caught smuggling drugs for profit and thus his only hope for survival was defecting with the aid of Arso? And then he could have an arc from coward to hero by the end when he chooses to sign on for the suicide mission? What if blind guy couldn't "feel The Force" he just used his senses to do all that crap? And then, at the end of the movie he feels The Force to dodge the blasts and flip the switch, which would also rekindle Machine Gun guy's faith in The Force. After all, how can he not believe at the start of the movie when he's seen all the stuff Donnie Yen can do?
Any way, those are just some quick ways I thought the characters could have been spiced up because as it stands they fall just short of flat. Essentially, the third act has to build up and resolve arcs for each of these characters, who for the most part, were not expounded on prior.
