Exactly. The problem with demanding that there be a "point" to every character's death is that death is frequently pointless and random. It's hypocritical and dishonest for a story to kill off faceless redshirts casually while never letting the audience lose anyone they care about unless there's some "meaning" to make them feel better about it. Every one of those redshirts was a very important person in somebody's story, important to their families and friends and loved ones.
That's why I admired what TNG did with Tasha Yar's death. She was killed off just as randomly as any redshirt, but for once they approached it honestly, let us feel the painful consequences -- the doctor's fierce, futile struggle to save her (infinitely better and truer to life than a two-second sensor wave and "He's dead, Jim"), the grieving of her crewmates, the struggle to move on with their duties despite the loss, their bitterness toward her killer, the tearful and cathartic memorial. Presumably the same thing happens offscreen when any redshirt dies, but for once ST was honest enough to let us live through it rather than sweeping it under the rug and having the bridge crew joking and laughing twenty-five minutes later. That's the meaning. That's the point. That no death is unimportant, that every life matters and every loss affects people whether there's some important plot purpose served or not.
(Which is why I deeply hate it that "Yesterday's Enterprise" denigrated Tasha's death as "pointless" and replaced it with a more cliched, juvenile fantasy of a "heroic" death. It's an insult to every rescue worker or firefighter or police officer who dies in the attempt to save lives. It's never meaningless or pointless to give one's life trying to help others, even if you fail to do so. Armus's act of killing Tasha had no meaning, but Tasha's choice to put her life at risk for others was a profoundly meaningful thing.)
It is one of the unfortunate facts of life that death is, almost universally, neither dignified or meaningful. Even those fortunate few who live to a ripe old age are often stripped of their dignity before death and those who die in wartime are very rarely allowed the luxury of heroic sacrifice. Instead, it is simply a tragedy they are taken from their loved ones and those they care about.
However, from a Doylist perspective, Star Trek is a work of entertainment first and foremost. In real life, Captain Spock would have perished in the generator onboard the Enterprise and never had the chance to form the Romulan Reunification Movement or visit San Fransisco. Commander Data would remain merely a backup on B4's hard drive. Harry Kim, O'Brien, and all too many other characters we know and love would simply have perished.
We cheat, however, because we love our characters. Sherlock Holmes didn't die at the bottom of Reichenberg Falls, Captain Kirk gets revived by the Borg (Shatnerverse alone, I know), Optimus Prime returns from battling Megatron, and so on because we can do that. With the stroke of a pen, Kathryn Janeway is once more commanding Voyager. This isn't bad, IMHO.
So yeah, I'm okay with keeping our favorite characters safe.
(Your point is well-received, Christopher, I'm simply venting because I've lost a lot of characters I really loved in Expanded Universes--from Mara Jade to virtually the entire cast of the previous DCU)