It's not just about having the power...

[Ibrîniðilpathânezel]

Originally Posted by Thinlómien

Are there other examples? I'm pretty sure there are, at least in the Sil, but I can't think of them right now. Furthermore, I have the feeling that we will soon have to define the word "power" or this debate will get all too messy...

I think Tolkien uses "power" both in the sense of physical or metaphysical might, but also (and possibly more significantly) as Authority, as in the power of a king over subjects, or of a general over armies. Either works in the debate, I believe.

Another instance of the negative effect of having power and not using it is the situation with the Valar and Melkor in the First Age and before. I wish I had the time to go dig up the pertinent quotes ('cause I don't recall precisely where they are), but Eru was not happy with the Valar hauling the Elves off to Valinor for safekeeping while they allowed Melkor to have his way with Middle-earth. He would have preferred that they deal with him more expediently, and trust in him to protect his Children. They had both the might and the authority to do so, but put it off and put it off until the confrontation inevitably caused tremendous loss of life and destruction to Middle-earth. If they had exercised their power much sooner -- say, when he destroyed the Lamps, before the Elves awakened -- much misery and woe would have been avoided later.