Go back and watch A New Hope again, trying to forget everything from Empire, Jedi, and the EU. Most of the characters are pretty shallow and one-dimensional there as well. The difference is that all of the Rogue One character had to die, so we don't get two movies of additional characterization.
That's actually one of the big reasons I rate RO so close to A New Hope, it's very similar thematically, save that it concludes with a Pyrrhic victory, and it does that without feeling derivative. We get just enough about each character to establish who they are, which is frankly all you need for a good one-off movie. Yeah, they're all a little cliched, but that's what happens when you need fast and dirty characterization. One seems a little YA dysopian novel protagonisty, one seems a little bargain-bin James Bondy, one seems a little Cowardly Liony, so on and so forth, but they feel like real people despite that and their interactions are genuine, their conflicts not contrived.
Like, here's A New Hope's main cast in one-line descriptions: virgin farmboy sorcerer, snarky rogue with a heart of gold, sarcastic warrior princess, wise old mentor, lone sane man (droid), comic relief who thinks he's the lone sane man (droid). Chewbacca is the only one who defies easy categorization, and that's largely because communication you understand by inference rather than directly tends to evoke more complex impressions.
Archetypes exist because they work. You're making a movie that's what, two to two-point-five hours long? You don't have time to really flesh out everyone who matters unless it's a film where you have one or maybe two characters who get the bulk of the screentime. So you fall back on narrative shorthand that the audience will quickly and implicitly grasp and let the characters speak for themselves-which is frankly often better than trying to spew out a massive backstory, especially when you've got a competent cast.