when President Nixon was considering aid for Tibet, he saw an image of Yamantaka, complete with horns, and judged that the Tibetan people were primitive demon-worshipers, understanding of the symbolism makes it clear that Yamantaka is a wrathful but compassionate Yidam, whose terrible power is turned against the obstacles to our practice, especially anger, hate, and death.
as stated on the page linked above, these are metaphors for beginners to use, they each have some symbolism in their posture, their number of arms, their dress, etc. each stand for various concepts as well as the non conceptual