wHy DiDnT tHeY jUsT tAke ThE eAgLeS iNtO mOrDoR?

A

1. Eagles aren't the chauffeurs of Middle Earth and generally don't intervene in the affairs of men. They're kind of like sub-angels, messengers of Valinor. It's like asking "Why didn't the angels just carry the Israelites to the promised land?" It's not their role.

2. They probably would have gotten caught. Sauron had flying messengers and spies of his own, not to mention the flying Nazgul he unleashed shortly after the Council of Elrond, right when the eagles would have been flying into Mordor.

3. The council explicitly states the reason for having a Hobbit walk it all the way is because it is a foolish plan that Sauron would not expect. While he didn't expect them to destroy the Ring at all, he'd definitely be on the lookout for any kind of visible approach like that.

4. Eagles are high and powerful creatures, and while I don't know if they'd even care about the Ring much less seize it, the point is made that you don't want powerful beings to bear it. Even Gandalf doesn't want to touch it.

5. Finally, and most importantly, remember what destroys the Ring in the end: Frodo's act of mercy sparing Gollum, which allows the Ring to be destroyed by fate when he tries to take it from Frodo. I don't think any mortal has the willpower to destroy the Ring...

If the eagles had just dropped off Frodo, it's very likely he would have seized the Ring rather than cast it into the fire. It took the journey to change Frodo from "I wish Bilbo had killed Gollum" to sparing him, having perhaps some foresight that he would have a role to play.