Answer:
Because the poem speaks of a complete generation that seems to be lost in between a long gone era of prosperity and happiness (supposedly) and the new times that are filled with insincerity, uncertainty, pain, anguish, and depersonalization. It is as if the speaker, the poet, instead of singing the praise of his generation, was rather howling —crying loudly like a lost and mighty animal in the forest— at the lost potential —but potential nonetheless— of his literary generation.