The folly of the Valar?

[Alda]

"And this [the sending of the Istari] the Valar did, desiring to ammend the errors of old, especially that they had attmepted to guard and seclude the Eldar by their own might and glory fully revealed"

It certainly seems like they are admitting that their over-protective act of bringing the Eldar to Valinor was rife with folly. Although I know they did it out of love like a parent might.

I often wonder why the Valar didn't forsee some of the problems that would arise by recognizing them in the different themes in the music.