[Boromir88]

But that said, and to return a bit closer to the original topic of the thread, I think there might be something about the desire for power and the structures that are built with the aim to dominate others that they are doomed to fail. I think that might be a kind of inherent "law" of the world, if you will. If you build, make or do something with the desire to dominate, it is a fall, and it is also going to fall apart, eventually. If you do it with a good aim, without the aim to control, it will last.~Legate

Indeed. In his story Tolkien says the worst evil of all is what he called the "domination of others wills."

The supremely bad motive is (for this tale, since it is specially about it) domination of other ’free’ wills.~Letter 155

Sauron is the prime example of this, but most of the great and mighty fall in LOTR, because they become motivated to bulldoze other free wills. There is an interesting dynamic between Saruman and Gandalf.

Saruman tells Gandalf:

"As the Power grows, its proved friends will also grow; and the Wise, such as you and I, may with patience come at last to direct its courses, to control it. We can bide our time, we can keep our thoughts in our hearts, deploring maybe evils done by the way, but approving the high and ultimate purpose: Knowledge, Rule, Order; all the things that we have so far striven in vain to accomplish, hindered rather than helped by our weak or idle friends. There need not be, there would not be, any real change in our designs, only in our means."~The Council of Elrond

Saruman no longer concerns himself with the "means" only the end to what he feels are now the "high and ultimate purpose: Knowledge, Rule, Order."

In contrast there is Gandalf, who has essentially already rejected the motivation to dominate other wills. In Bag End, Gandalf makes clear he could "make" Frodo give up the Ring by force:

Gandalf laughed grimly. 'You see? Already you too Frodo, cannot easily let it go, nor will to damage it, And I could not "make" you - except by force, which would break your mind.~The Shadow of the Past

Gandalf does not seek control over anyone's free will. To do so, even if it would serve the "greater good" would be a supremely bad motive, and it's that motive which lead to the fall of the great and mighty. It makes you wonder, if push came to shove, and Gandalf was with Frodo in the Sammath Naur. Would he still reject "making" Frodo destroy the Ring? Would he bulldoze Frodo's will (although by this time you could say the Ring had already bulldozed Frodo's will) for the "greater good?"