To answer Yash’s question, I believe it is due to the moral impurity of people in our time. The people of Lord Buddha’s time were much more virtuous than the people of now. This was why their era was the golden age of the Ariyas. Devas (those of good gati) tend to show themselves to those who are virtuous. Those who develop jhanas can see them very well I believe.
A Quest to Recover Buddha's True Teachings
