The character of Leia has had a rough ride outside the films– and I’m not just referencing her horrifying cameo in the Star Wars Holiday Special.
Maybe writers can’t strike the balance between princess and soldier very well. Maybe Carrie played the character so strongly the bar was too high to duplicate (I personally believe the last one).
Until very recently, no Star Wars book had successfully captured her worshipfulness as she really was in the films. In 1978, Splinter of the Mind’s Eye was released by Alan Dean Foster, and Leia is a near-worthless damsel throughout the whole story (described in one scene as a steel kitten). As I’ve described elsewhere, her character becomes a mere plot point to push forward Luke’s heroic exploits. While she can handle a gun, she regularly slips into the innocent sex object for her (then unrelated) companion to gawk at.
It doesn’t get better in later books. The Courtship of Princess Leia centers around the idea that Leia needs a man, and must choose between marrying dashing Prince Isolder or charming Han Solo (the latter of whom lies to get her alone on a planet so he can change her mind– she was originally set to marry the prince).
In the following books Leia repeatedly needs to be saved by Han, or alternately, by Luke, making her own strength worthless by comparison. Apparently writers sought to bring the multifaceted Leia to life by choosing a single facet to fit the scene. So Leia– who is a politician, a smuggler, a general, a Force user, a mother and a wife– found herself cycling infinitely between all of these roles while never really being all of them at once. The result of all the role juggling is jarring, like replacing an actress on a show halfway through the fifth season and expecting the audience to believe it’s the same person.
The only time Leia genuinely appeared the wry, amused, uncompromising character we know and love was in Claudia Gray’s recent novel, Bloodline. With the old canon gone, Leia’s character underwent a dramatic– and necessary– simplification. She was Force sensitive, but had never trained to use the Force, and didn’t need to. She was a politician first, and a smartass second. She knew how to use a blaster, and the one time Han shows up to save the day, she doesn’t need it.
That’s the Leia I know.
Leia’s treatment in previous books doesn’t make them bad stories by default. A lot of them are quite good– the Legacy of the Force series is a prime example. But Star Wars deserves a better class of princess than what we were given in the Expanded Universe. And in a galaxy full of Ahsokas and Padmes and Jyn Ersos and Reys, it’s difficult to argue that it can’t be done.