Why did the Buddha not teach about the origins of the universe?

Cula-Malunkyovada Sutta: (The Shorter Instructions to Malunkya) MN 63

The monk Malunkyaputta is troubled by the Buddha's silence on metaphysical questions, which include queries about the nature of the cosmos and whether the Buddha exists after death. Malunkyaputta then meets the Buddha and asks him for the answers to these questions, saying that he will renounce the Dhamma if the Buddha does not provide the answers. 

The Buddha uses the story of a man who has been shot with a poisoned arrow but refuses to have it removed until he is informed on the details of the arrow and the man who shot it. The Buddha said that the man would die before his questions can be answered. 

Similarly our immediate problem is our suffering in life. Life is so short. It must not be spent in endless speculation about the origin and nature of the universe and other metaphysical subjects that does not bring us any closer to the truth. Instead, our efforts should be made to overcome suffering..

"It's just as if a man were wounded with an arrow thickly smeared with poison. His friends & companions, kinsmen & relatives would provide him with a surgeon, and the man would say, 'I won't have this arrow removed until I know whether the man who wounded me was a noble warrior, a priest, a merchant, or a worker.' He would say, 'I won't have this arrow removed until I know the given name & clan name of the man who wounded me... until I know whether he was tall, medium, or short... until I know whether he was dark, ruddy-brown, or golden-colored... until I know his home village, town, or city... until I know whether the bow with which I was wounded was a long bow or a crossbow... until I know whether the bowstring with which I was wounded was fiber, bamboo threads, sinew, hemp, or bark... until I know whether the shaft with which I was wounded was wild or cultivated... until I know whether the feathers of the shaft with which I was wounded were those of a vulture, a stork, a hawk, a peacock, or another bird... until I know whether the shaft with which I was wounded was bound with the sinew of an ox, a water buffalo, a langur, or a monkey.' He would say, 'I won't have this arrow removed until I know whether the shaft with which I was wounded was that of a common arrow, a curved arrow, a barbed, a calf-toothed, or an oleander arrow.' The man would die and those things would still remain unknown to him."