Uh, you might have hit on the issue without realizing it.
Leia was a well-drawn character with a compelling actress playing her. There was no sense in which she was added in just to stick a woman in the movie. That was part of it, but she was interesting and held her own.
Speaking only for myself: I think they did a horrible job of developing the character of Finn and I felt like TLJ would have been stronger and moved along better without Rose and her entire throw-away storyline that goes nowhere except a chemistry-free relationship with Finn. It all ends up feeling like they threw in certain characters for the sake of making a statement but didn’t bother to develop them.
That’s different than being “angry about diversity” in the movie. That’s a popular thing to post these days but I think isn’t accurate for the vast majority of those who were less than thrilled with TLJ. People just give the nuts who do have an issue with diversity in and of itself WAY too much attention... often for their own motives.