ACKSHUALLY, it has more to do with:
Mount Doom not having an open top (at least in the books). The Crack of Doom was only accessible by entering a door and going deep into the mountain.
Sauron controlling the weather around Mt. Doom, and being able to kill any Eagle that came near it.
Sauron having flying Nazgul patrolling the sky around his fortress.
Sauron being able to see a bunch of giant Eagles coming thanks to natural and supernatural sentries, and sending his Nazgul and a giant fuck-off army to defend the one doorway into Mt. Doom.
The central theme of the LOTR, which is that sometimes the most important people aren't the biggest and most powerful, but the smallest and most subtle. The God of the LOTR universe basically made Hobbits as a crack stealth squad which could be used to sneak the One Ring past Sauron's Nose and into the Cracks of Doom, which themselves were lightly guarded because Sauron figured (a) the door to the Cracks was close enough to him to be secure and (b) no one who had the One Ring would ever want to destroy it. (To be fair to Sauron, Eru/God had to rig one of the Hobbits to self-destruct in order to get the Ring into the Lava Pit, so technically, the Dark Lord was right about that.)
Sorry to get heated, but that whole "Eagles won't help the heroes because they're huge jerks" argument irks me. Mostly because the Eagles were fairly interventionist when it came to other situations. The real reason the Eagles wouldn't help; weren't even suggested by Gandalf as a potential source of help - is that Eagles aren't stupid enough to go on suicide missions.
What were we talking about again? Oh yeah... Star Wars....
Star Wars was a Fantasy movie with Sci-Fi elements. It managed to remain consistent with its universal rules throughout the first trilogy. At no point did the Jedi's powers break the setting. We didn't see anyone teleport from one place to another like in Star Trek, because if we had, we'd be forced to wonder why people bothered traveling in hyperspace. We never saw the Jedi do any crazy Harry Potter transformation shit, because such things belong in a universe that's higher on the "magic just makes things happen" scale, like how Elsa can make an ice castle and a new set of clothing in Frozen despite knowing nothing about architectural design or creating/dying/decorating fabric.