“The question I have, and this applies to anyone who claims extra-Scriptural revelation, is why it took so long for this to be made known?”
What exactly is the ‘this’ you think took so long to be made known? We believe gospel as we teach it is what Christ and the apostles taught, but as the church fell into apostacy some things were lost and some things were changed and some things were added. We believe our church to be a restoration of original Christianity.
God didn’t just sit around and wait till 1820 to start the restoration either, he was preparing the world for it all along. The Reformation and the weakening of the power of the Vatican was part of preparing for the Restoration, the formation of the USA with it’s freedom of religion was another major building block.
Those who didn’t get a chance to accept the fullness of the gospel in their life will get that chance between death and the resurection. Even if you don’t believe there was an apostacy, the fact remains that billions upon billions of people through time (and even today) die without even hearing the gospel. By the time we get to the judgment, everybody will have had a fair chance no matter when or where they were born to make it to heaven.
It appears that the LDS organization is very similar to EVOLUTION:
There is NOTHING that can't be used to feed into expanding and explaining it's existance.