Why Do We Need the Priesthood?

I've made some progress in my lesson plans. I'm currently planning to take the same approach to the restoration of the Priesthood as the missionaries take with the lesson on the Restoration. Basically, I'm going to teach my students that the Priesthood (being, basically, the authority to act in God's name on the Earth) is essential to perform essential, saving ordinances and organize and lead His church. Jesus had that authority, with which He organized the church nearly 2000 years ago, and He gave it to His Apostles, who used it to lead His church until their deaths. When the Apostles were martyred (I may not go into detail on that point), the Priesthood was lost from the Earth, and it needed to be restored.

But here's the tricky part: I'm not entirely sure why the Priesthood needed to be restored. I know we need modern revelation, but it turns out that we don't actually need to have the Priesthood to receive revelation. Joseph Smith proved that when he walked out of the Sacred Grove having seen God Himself, nearly a decade before he received even "the Preparatory Priesthood." He didn't need to hold the Priesthood to receive the vision that changed the world, so receiving revelation isn't the reason we need the Priesthood.

I know we need the Priesthood to perform essential ordinances, but I have no idea why those ordinances are essential. For example, Elder Oaks once said that he wasn't sure why baptism is essential, other than, basically, because God said so. Why do we need to be baptised? Why do we need temples? Yes, temples are needed to perform ordinances for the dead, and the gift of the Holy Ghost is a nice perk, but we don't know why the dead need to be baptised any more than we know why we do, and we can receive impressions from the Holy Ghost even without the gift of the Holy Ghost; it's just less consistent. Other ordinances, like blessing the sick, aren't essential at all. Healing is great, but death is inevitable anyway, and anyone can pray for, and receive, miracles, including healing miracles, whether they hold the Priesthood or not.

During my mission, the question of why we need the Priesthood hadn't occurred to me. I thought we needed the Priesthood because we needed prophets, because we need the modern-day revelation that only prophets can give, but revisiting the Joseph Smith story has reminded me that we don't need the Priesthood to receive revelation, so we must need it for some other reason, and I'm suddenly not entirely sure what that reason is.

It could be that we need the Priesthood (i.e. the authority to act in God's name on the Earth) in order to organise and lead His church. This make sense. After all, if someone wanted to make an organization in my name, I should hope that they would need my permission to do so, and if someone other than me is going to run my organization, they would certainly need my authority to do that. Perhaps that's the angle I'll take with the kids this Sunday. Joseph Smith needed the Priesthood because he couldn't perform ordinances or lead the church without it (never mind that we're not quite sure why we need those ordinances).