To Mormons, Joseph Smith was a martyr.
The way the story was told to me in years and years of Sunday School was that he was being held in jail because closed-minded anti-Mormons hated him. Then a mob ambushed him and his friends and martyred both he and his brother. There are a few important details and relevant facts missing from this story.
First, there was never really an adequate description of why Smith was jailed. But early church history is rife with stories of persecution, so when the Sunday School teachers told us he was unfairly jailed because people hated his guts, we believed it. What we never heard about was Smith's violent attempt to quash the Nauvoo Expositor or the charges brought against him for polygamy and treason (among other things).
I can understand omitting that from the story. If you're trying to convince someone that Joseph Smith is a hero and a martyr, then you might as well skip the parts that make him look bad. Sure, you're putting a biased spin on the story, but at least you're doing it for an good reason.
Second, there was never a mention of the fact that Smith had a gun and that he used it to fight back. I don't understand the omission of this because it doesn't make it look bad. Sure, Joseph Smith had done some bad stuff, but he was in jail awaiting his trial, and everybody knew he was at risk for assassination. So they smuggled a gun in so he could protect himself. And when a bunch of guys tried to kill him, he defended himself. There is nothing morally reprehensible about that.
Just in case someone misunderstands and thinks that he was a violent person, we're gonna skip the part about the gun? The church is way too concerned with PR and goes so far as to nearly deify its founder in the process. There's even a nice seminary video depicting Joseph's martyrdom and--gasp!--he is unarmed. There is, however, lots of mournful music and soulful posing.
It's easier to see him as perfect, incorruptible, and heroic if he's the victim. It's easier to see the mob as hateful, fearful, evil people if they kill him when he's unarmed. It's easier to brainwash people into Smith's church if you spare them the whole truth and whitewash what's left.
And that doesn't seem right to me.