I think the title pretty much explains everything you need to know here. I will give an explanation for my summing up of each different story.
The entire Harry Potter series: “Accept the reality of death and you will lose your fear of it.” Explanation: Not doing this is Riddle's mistake.
The Fellowship of the Ring: “Beware of tall strangers wearing long dark cloaks.” Explanation: The Ring Wraiths, of course!
The Two Towers: “Don't cut down trees” Explanation: Well, just look at what happened to Saruman when he did.
The Return of the King: Two wrongs can make a right. Explanation: First wrong: Frodo selfishly decided not to destroy the ring. Second wrong: Gollum selfishly tried to steal the ring. Right: the ring ended up destroyed.
The Neverending Story: Don't change if there is nothing truly wrong with you in the first place. Explanation: Bastien did this, and nearly lost everything important to him.
The Childe Cycle: The ends don't justify the means. Explanation: Bleys's fault is that he believed they did.
The entire works of Terry Pratchett: Humor is often the vessel of profundity. Explanation: Read them and you will understand.
The Chronicles of Thomas Covenant: No one is perfect. Explanation: Again, you must read them to understand.
The Belgariad, The Mallorean, The Elenium, and The Tamuli: Good triumphs over evil.
Explanation: Pretty basic one here.
The chronicles of Alvin Maker: Don't force people to live under other people's shadows. Explanation: Look at what Calvin became when he was.
Ender's Game: Hiding the truth can be traumatic for children. Explanation: I don't think this explanation is necessary.
I have to say, the one on Terry Pratchett is pretty spot on!
Not to say that I don't agree with them all.
You don't have to point out any one thing and assume that I think it is to the exclusion of other things. This age is far to polite for its own good, and apparently you are no exception :) .