Why do corruption and immorality from 175 years ago matter today? Because it has continued in a new form.
The latest essays (1 & 2) from the LDS Church admit to a lot. They've not admitted everything that so-called anti-mormon (but thoroughly accurate) historians have dug up about Joseph Smith, Brigham Young and more. But it is enough.
The few confessions about Joseph Smith's sexual immorality affect the plan of salvation preached by the LDS Church. It claims to be led by prophets who are inspired by an all knowing God that leads us morally. God knows truth, and teaches it to the prophets, goes the claim. But the people he supposedly chose to lead were and are hugely immoral. The plural marriage law God sent down, thrice from an angel with a drawn sword, is corrupt. That revelation told Joseph Smith to conduct illicit sexual harassment and have multiple simultaneous sexual relationships with married women, with young teen girls and often in secret behind Emma's, the legal wife's, back.
God's angel told Joseph to do these things or else be destroyed. Either that, or Joseph made it all up.
If God did it, then the Mormon version of god is an unethical, immoral being--the way he treats women (and blacks, and gays and ex-mormons and...) is sickening. If the imperfect Joseph made it up to get his horny on, then how can you trust such a pervert who would destroy marriages and young teens in his lustful pursuits? How do you know his other so-called revelations from angels weren't just made up likewise?
We know he was sexually corrupt. We know he couldn't translate regular Egyptian (so the Book of Abraham came from "revelation" akin to an angel with drawn sword). We know he fictionalized bits of history on ancient America that are completely overthrown by modern science. We know he was involved in a Kirtland banking scandal and had short-lived plots to overthrow the U.S. government.
Joseph Smith knew his actions were viewed by his 19th century peers as immoral and scandalous. He tried to hide his dalliances and even his "revelations". Joseph Smith used code names in the original Doctrine and Covenants to keep the latter-day saints activities secret from non-Mormons. The revelation on plural marriage was kept very secretive, and (according the LDS essay on the topic) the controversy caused "leaders to issue carefully worded denials that denounced spiritual wifery and polygamy but were silent about what Joseph Smith and others saw as divinely mandated “celestial” plural marriage."
Joseph's church lied even to their own members--that, "the Church practiced no marital law other than monogamy while implicitly leaving open the possibility that individuals, under direction of God’s living prophet, might do so." When the essay says, "implicitly leaving open the possibility" it means that the secrets were known to some, but not all.
Joseph Smith lied about his ability to translate, hid his immoral "wifery", surreptitiously plotted to increase his power with an elite Council of Fifty, and so forth.
With full disclosures on these, you can't actually expect non-Mormons to buy that this man or his god are worth following. Why are modern LDS defending Joseph Smith? Don't they know better now that their own church was practically forced to confess Smith's sins? They couldn't hide it any longer, half a century after the meticulous record produced by a woman, Fawn Brodie, in No Man Knows My History, and the several other fantastic books since.
The forced confessions at LDS Inc are too little, too late for many who have "jumped ship". And we're not going back.
Modern LDS hold on to the side rails of their sinking gospel ship. They believe the current leaders are a moral compass, dodging the icebergs of gay-marriage and wanton immorality in the latter days. (Even as they crash into Joseph's chilly immorality and the icy racism of prophets past.)
But these same men--the Mormon prophets today--are still defending the indefensible. The corrupt and immoral foundation of their church continues in a new, but still secret form. The modern prophets continue in corruption, spending billions on profitable ventures in non-charitable ways. They pile on profits and suck out true charity to only spit it out in miserly, paper-thin disclosures.
These modern prophets are just as corrupt as Joseph; perhaps more, because they hire extensively notable legal teams and maintain better secrecy on their activities. For now.
Financial secrecy is a confession that will come. These men will be viewed just as morally bankrupt as Joseph and Brigham. But for now, LDS lawyers and non-disclosure agreements keep the Mormon faithful on course in their ship.
Historically, it was the secrecy of polygamy that troubled Mormons and their investigators. Members sigh with relief it's no longer practiced. Today it's the financial secrecy that should keep LDS awake at night.
Wake up, members. You can't trust these men.
The restoration was made up. It seems magical and marvelous. If you research, however, you'll find it's been polished over the years. Your Doctrine and Covenants was transformed by later "prophets" again and again. Your Book of Mormon was edited and corrected 4,000 times since Joseph Smith published the novel. These men are blinding you to the real past, and you trust their claims that Joseph was inspired to do something no one could have done in the early 1800s. Because he didn't--the magic are the edits to his work along the next century.
What was inspired was the polishing Smith's and Young's turd by the next ten prophetic administrations and not telling you about it. Now they keep financial secrets while collecting massive amounts of LDS income to build...what are they building this month?
Oh yeah, this elite condominium investment property. (And you thought I was going to point out the mall.)