Doom of the Noldor

[Nilpaurion Felagund]

I just don't understand why the Avari become weary of the world. (Alchisiel)

Men would dominate the world. The Quendi want status quo in Middle-earth preserved, as seen in Galadriel's use of Nenya in Lothlórien. Men, on the other hand, would change the world. It's partly due to Eru's gift . . .

Therefore [Ilúvatar] willed that the hearts of Men should seek beyond the world and should find no rest therein; but they should have a virtue to shape their life, amid the powers and chances of the world, beyond the Music of the Ainur, which is as fate to all things else; and of their operation everything should be, in form and in deed, completed, and the world fulfilled unto the last and smallest. (QS I)