So, here's the thing. I think the statement of "But they've always been kids movies!" is kind of a cop-out. I've heard it for years, especially after the Prequels. When someone criticizes the characterization in one of the films, the response is often "Oh whatever. They're just dumb kids movies anyway. Stop taking it so seriously!"
And it's true that Star Wars -- the OT especially -- was a mostly plot-driven tale in the tradition of grand space opera/fantasy. It's not meant to be MacBeth. But that aside, I think it's reasonable to expect characters to be drawn in an interesting way that allows for a compelling performance. And even in a plot-driven piece, your story simply becomes better if it contains well defined characters, ideally with some degree of complexity to them (because that makes them more human and relatable), and if their actions conform to who they are as characters. If that means you write your characters to fit the plot you've envisioned, then fine, do that, but write those characters well.
I've only seen Rogue One once, but I really enjoyed it when I did. (I own it, but haven't gotten round to re-watching it yet.) I think with Rogue One, you're dealing -- by necessity -- with somewhat less defined characters, simply because of the amount of time you have to tell your story, and how that constrains your ability to really dig in to who these people are and what makes them tick. So, instead, I chose to view the film as basically the Star Wars equivalent of The Dirty Dozen, where you get only a little about the characters during the film, with most of the focus on a few specific ones, while the rest are just kind of background material defined by what amounts to a character outline.
And I loved the fact that it was a TPK. I mean, it would've been nice to see maybe a couple survive, but I was perfectly fine with the TPK quality and the high number of casualties. I like that it showed the cost of the war, and that the Rebels didn't always win with a slam-dunk and a happy ending.
And I'm gonna go on record and say that I think it actually has a better space battle than ROTJ.