It is always dangerous to write about a topic that is inextricably tied to so many people's identity. I suspect most Mormons view themselves primarily as an eternal family, so the temple can be quite a sensitive subject. I will try to be as respectful as possible to everyone's beliefs and ask in advance for your forgiveness if I offend anyone.
This is also a sensitive topic because it deals with people's marriages. I certainly wouldn't appreciate someone saying to me, "Hey Ned, those icons at the Orthodox church where you were married are totally idolatrous!!! And the man who performed the ceremony was practicing priestcraft! Nehorite!" For good or bad, my marriage is part of my identity, and I will defend it against all comers.
For this reason, I'd like to set aside the topic of sealings, which are a source of great comfort and happiness to a lot of good people, and of which I have no first-hand knowledge anyway. I'd also like to skip over baptisms for the dead. I've always liked the idea and the practice of baptisms for the dead and had good experiences performing them (although perhaps because I envy being baptized as an adult). I'd like to focus instead on the endowment, and perhaps offer comfort to those who, like me, didn't seem to have the same spiritual experience as everyone else.
Part of the problem of the endowment, I believe, is overselling. We fall too much into the Homer Simpson trap of, "I don't want to oversell it, but it's better than ten Super Bowls!" Even the name leads us to believe that we'll be given a huge gift of knowledge. I'm sure some people do find great, hidden meanings in the ceremony, but I was never one of them. In my experience, the endowment presents a fairly straight-forward creation story/allegory, not all that different from the accounts we have in Abraham, Moses, and Genesis. Why do we oversell it? Because we can't tell anyone what exactly goes on, which leads to overstatement.
The atmosphere of secrecy around the temple has always bothered me. This might have made sense in the Joseph Smith-era, as the practice of polygamy was hidden. It is much harder to justify in our electronic age, when anyone who cares can find a copy in .2 seconds. Ironically, the Internet has made the ceremony available to everyone BUT faithful Mormons. For a long time, I wanted to know what changes were made to the ceremony in 1990. I had always heard about them, but I had no legitimate means of finding out. Short of cornering an old-timer in the Celestial Room, there is no way for faithful members to discover this information. I finally gave up, and googled it. I had all my answers in 60 seconds. I might have felt guilty if this information was reserved for recommend holders, but it's not. Even they don't get to know.
A second concern I had when I went through the temple was the heavy-duty promises I was required to make. Maybe some good temple prep classes spell out what those commitments are, but I was not prepared beforehand. I'm certain that I still would have gone through the temple, but it would have been nice to have a sheet saying, "these are the four promises you are going to make." Because we are afraid that everything temple-related should be secret, we allow people to go in unprepared, which I think is unfortunate. Just as we should be aware of what our baptismal covenants are before we get baptized, we should also have more than 10 seconds to decide whether we want to commit all our resources to the church. Has anyone ever left in the middle of an endowment because they didn't want to make these promises?
Lastly, I remember being quite disturbed on my mission when I discovered the heavy Masonic influence on the endowment ceremony. Once again, I had absolutely no clue. Frankly, I felt deceived. By avoiding and glossing over these topics, it seems to me that we are only postponing the day of reckoning for many of our coreligionists. Maybe 95% will never care about these things, but for the 5% who do, it can be devastating. Obviously, in the Internet age, there is now a ton of information on Masonry and Mormonism that I didn't have, but besides FARMS apologias, precious little comes from the church. What I wouldn't give for a General Conference talk explaining why our salvation is couched in such foreign Masonic terms. Is it because that was what Joseph was familiar with? Does Masonry have any relevance to us today? Why not if it is so entwined with the Endowment?
I think the root of all these problems is the same: secrecy. If we were more open about the temple, most of these problems would go away. Unfortunately, in the dark, the truth often struggles to get out.