Why Is The Lord Of The Rings One Big Deus Ex Machina?
You know the Grand Theft Auto cheat codes that let you just drop a jet plane in the middle of the streets so you can zoom out of the five-star wanted level you just dipped yourself in? That's kind of what the Eagles are in Lord Of The Rings. Whether its Bilbo and his dwarf crew being saved from goblins, them coming down to even the odds in the Battle of Five Armies, Gandalf being saved from Saruman by them, or them rescuing Frodo and Sam from Mount Doom, the Eagles kind of seem like they're there to provide a Band-Aid to the narrative problems that J.R.R. Tolkien created for himself. That way he could focus on more important things, like looking impressive while smoking a pipe. Tolkien came out of the womb with a freshly packed bowl.
This leads people to say, "Why didn't the Eagles take care of [insert dangerous task here]?" Most commonly, that hypothetical dangerous task is delivering the One Ring to Mount Doom so that it can be destroyed. And those people haven't been paying attention to any part of the movies. They were probably staring at the majesty of Liv Tyler, or wondering if Gimli gives good hugs. I bet he does. I bet it's like hugging a wool blanket, and I bet it smells like good beer, sawdust, and hope.
For instance, remember one of the most important parts of the Fellowship Of The Ring, when Frodo offers Gandalf the Ring and Gandalf tells him, verbatim, "DON'T GIVE ME THAT RING, DAWG. I'M FRIGGIN' GANDALF." He doesn't do that because the Ring will give him a rash or because it doesn't match his magic bathrobe; he does it because he's Gandalf. If that Ring gets to him and turns him evil, imagine all the damage that he could do. He'd kill Frodo, and then eat all of the delicious Hobbit cakes, and then torch the Shire with a fart.
So no, the Eagles should not be taking that ring to Mount Doom. They're magical animals, but more importantly, they're 30-FOOT MONSTER BIRDS. If Gandalf, who has things like willpower and talons that aren't as long as your torso, doesn't want to take the Ring himself, I don't think Plan B should be to give it to the pterodactyls. That would set you back a notch. If you give it to Frodo, you at least don't have to worry about his little Hobbit hands going on a decapitation spree if he gets an itchy ring finger. If you give it to the Eagles, you just add another book to the series: Fellowship Of The Ring, The Two Towers, Return Of The King, and Argh, My Eyes! They Took My Eyes!
Of course, the followup argument is "Just let Frodo keep it, but have him ride the Eagles!" Same problem. If Frodo turns, wouldn't you much rather have him on foot, surrounded by companions who could easily destroy him, rather than slapping him on the back of a gigantic Eagle? Not only would he be able to more easily escape his group, but now he commands a squadron of gigantic, and very possibly invisible Eagles.