But the more I read through things, the more I sense that JS stumbled into it with no real foresight and no plan at all. I tend to agree with Pup that once the ball was rolling, it just rolled him up and took him with it.
One thing worth considering is the context of how a lot of people came to religion at the time. This was the era of wild, multi-day camp meeting revivals, and the idea of having a religious, conversion experience was common enough that there was social pressure to do it, and somehow, people managed to comply. Religion wasn't necessarily a dry, calculated decision.
From a couple longer articles on revivals in New England in the period:
http://www.teachushistory.org/secon...ligious-revivals-revivalism-1830s-new-england
The excitement of the prayers and preaching caused many people to be "slain," that is fall prostrate in front of the stand; or to dance, shout, and clap their hands. At times people spoke in tongues.
http://www.crookedlakereview.com/books/saints_sinners/martin7.html
Finney used many of the emotionally arousing techniques in his early revivals, practices which had been successful in frontier Ohio, Indiana, and Kentucky, on the real frontier. In time he tried to avoid the excesses which were typical of those mid-Western frontier revivals which led to convulsions, trances, and mass hysteria. In Kentucky, for example, under the excess of emotion whipped up by energetic preachers, converts would get down on all fours and "tree the Devil" and bay like hounds at the foot of the tree. In frontier revivals, psychogenic ills could be cured—or caused. Finney avoided the extremes of this type of revivalism.
So you had people who were seeing visions, fainting, acting hysterical, and New York state was just barely a notch below the wildest stuff at Cane Ridge, KY, for example. This was what teenagers were doing, instead of going to rave parties.

And it was socially acceptable for all ages--even praised.
People didn't necessarily always have their experience right at the revival. Going off into the woods to pray and work through their problems alone was another common behavior.
Joseph Smith's famous "first vision" is well within the norm for this kind of thing. You can see an account of it here:
http://www.lds.org/library/display/0,4945,104-1-3-4,00.html
A random similar example of prayer alone in the woods that leads to a spiritual breakthrough, though not quite as vision-like:
http://books.google.com/books?id=JaGg2kz4j3cC&pg=PA206&output=html
Smith took it farther than most young men, who just contentedly joined the local Methodist Church or whatever, after having their big breakthrough experience. But he seems to be someone who was peculiarly gifted with imagination and fantasy, and it's natural that he interwove all that with the fervor of religion that was expected at the time.
He reminds me of the kind of young man today who's so into a superhero or a computer game or whatever, that that's all he talks about, knows all the characters, all the details, dresses up for the conventions. On one level, he knows it's not real, and he may also be a computer hacker and swindling people at the same time because he's darned smart and enjoys the risk and excitement of the black hat stuff (no pun intended), but on another level, he gets a boost from
pretending it's all a real grand adventure, and the emotional reward is just indescribable.
And it just takes over his life.