[lindil]

I think the major cause of the initial delay ws that the making of the Sun and Moon had to happen right after the death of the trees. that was a project whose significance was to last for the rest of the earth. Once the Kinslaying occured and the Valar offered the Noldor one last chance to repent before they left Aman, it was inievitable as the prophecy of the North shows, that no help would come till the Noldor had spent themselves. If they were determined to make war on Morgoth without the aid or blessing of those who dhould have and did no better, then the valar did the least they could do which was warn them of the cost of their folly, and offer them one last way to avoid a hopeless war. 1/10th of the Noldor showed they understood the bigger picture. As did galadriel soon after [quite probably due to Melian's influence. She had already told Thingol it was hopeless, and he was resolved ot stay minimally involved].
So of the various royalty involved, quite a fwe chose not to entangle themselves in the Hopeless war, [though Thingol later became ensnared due to his cruel jest with Beren].