Why the Gods no longer speak

Everyone knows that the Gods used to answer prayer and preform great deeds in Adar. All worshipers can agree on this matter, wether they venerate Sol, Selene or Astarte. Even the elves might agree that powerful beings once interacted with this world, but do so no more. Why?
Different cultures and religions tell different stories. Some say that the Gods left, angry at the sinful nature of Man. Others say that the Gods are still with us, observing mortals, waiting for some event, or perhaps testing the faithful with their silence. Some say the Gods fight amongst themselves, and have made the Material Plane a neutral ground; where no-one divinity may thread, lest they be prepared to face the wrath of all the others. Others still proclaim that powerful mages, arrogant practitioners of the Arcane arts, poisoned this world so that the Gods no longer come here. 
Whatever the truth, the fate of this world appears to be in the hands of mortals.