Character death is a problem in the Star Wars Expanded Universe. It's not that there isn't enough of it, but that the writers are killing the wrong characters. Unwilling to let go of the major characters from the Star Wars films, EU writers have turned towards the Next Generation characters, killing off the people most needed to continue the Star Wars story.
The first Rebel character from the Star Wars films to die in the Expanded Universe was General Crix Madine, executed by the Imperial Remnant in Darksaber. Gradually, other heroes of the Rebellion passed on: Admiral Ackbar died of old age, and Mon Mothma passed away after a long illness. While minor characters from the films and characters introduced in the Expanded Universe were not safe from death, however, major characters were left untouched.
As the EU went on, it became apparent that someone had to die. The transfer of the Star Wars novel license from Bantam to Del Ray was a turning point for many reasons, but the biggest was the arrival of a darker, more dangerous Star Wars universe, and a shocking death was needed to make this more realistic. Still unwilling to kill one of the Big Three -- Han, Luke, and Leia -- they compromised by killing Chewbacca. Whether or not this death was a good idea, it certainly served its purpose, setting the tone for the upcoming story arc of the Yuuzhan Vong invasion.
And yet, twenty in-universe years later, the rest of the main characters are still alive and well.
Superannuated Skywalkers
The problem with the EU writers' refusal to kill any of the Big Three is twofold. First, the characters keep getting older, and yet show no signs of aging other than a few gray hairs. At the age of sixty, Obi-Wan Kenobi had gone completely white and was noticeably handicapped in his fight against Darth Vader in A New Hope -- a duel in which he was defeated. In The Phantom Menace, Qui-Gon Jinn seemed spry enough at the same age, but still didn't live past his duel with Darth Maul. In fact, it seems that few human Jedi live to old age simply due to the nature of the job.
In the Legacy of the Force and Fate of the Jedi series, Luke and Leia are in their sixties and Han is pushing eighty. Luke is still an active Jedi warrior, and Leia is a skilled Jedi Knight despite not officially taking up that mantle until her mid-fifties. Characters have stated that human life expectancy in the Star Wars universe is longer than ours, with an average lifespan of over a hundred -- but one would still expect the characters to show some signs of aging.
The other problem is that the writers have to kill someone in order to keep up the tension: situations seem much less dangerous and exciting when the readers know that the main characters are protected by contractual immortality. Unable or unwilling to kill off the Big Three, writers have turned to the second generation characters instead. Anakin Solo, Han and Leia's youngest child, died at only seventeen in Star by Star. His brother Jacen Solo was killed after he became a Sith Lord -- admittedly a gutsy move in a universe where characters regularly turn to the dark side and return to the light with no consequences.
The Next Generation
What the Expanded Universe needs is for writers to move away from the main characters of the Star Wars films and allow the next generation characters to take over the story. The EU appeared to be moving in this direction for the New Jedi Order, which featured the Solo children as central characters, and Legacy of the Force, much of which centers on Luke and Mara's fourteen-year-old son Ben. But as of Fate of the Jedi, only Ben and Jaina are left of the next generation. What happens to them when the writers need another dramatic character death?
When it comes to storytelling, there is little reason not to let go of the Big Three. Expanded Universe stories featuring minor and original characters have been largely successful, from the X-Wing comics and novels of the early EU to comics such as Star Wars: Legacy, Dark Times, and Knights of the Old Republic and novel series such as Coruscant Nights and Darth Bane. In addition, EU writers are continuing to write stories out of chronological order, returning to the time of the Original Trilogy and the early New Republic and filling in the gaps with new novels and comics. Even after they die, Han, Luke, and Leia will still be available for new stories.
Bottom line: the heroes of the Original Trilogy cannot live forever. No matter how they die, fans will complain about it; that's just an unavoidable truth of fandom. But the longer they go without dying, the more tedious and unbelievable their stories will become. The Star Wars Expanded Universe cannot move forward until the writers -- and the fans -- are willing to let go of the Big Three and allow new characters to take center stage.