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[Mat_Heathertoes]

I'd add to that the Valar feared to attempt to wrest control of Middle-Earth again by force as they did when they overthrew Utumno in the Ages of the Trees to the aid of the Elves. In that war Middle-Earth was broken and ruining in many places and the Valar feared to do that to mankind who were acknowledged to be 'more frail, more easily slain by weapon or mischance'

It does state however in 'Of Men' - Chapter 12 of the Silmarillion that:-

'To Hildorien there came no Vala to guide Men, or to summon them to dwell in Valinor; and men have feared the Valar, rather than loved them and have not understood the purposes of the Powers, being at variance with them, and at strife with the world. Ulmo nonetheless took thought for them, aiding the counsel and will of Manwë; and his messages often came to them by stream and flood. But they [Men] have not skill in such matters,...

I'd say Men were a mystery to the Valar and after the fiasco of the previous summons of the Elves to 'come holiday in Valinor' , they decided to leave well alone until they understood Mankind further .. even the Powers made the odd mistake or two ....