Rabbi Yankel Galinsky replied that he has two answers.
The first answer is with a parable.
There was a Tzaddik who worked on himself and was meditating. He thought to himself, Moshe Rabbeinu was human just like me, he purified himself like a Malach, arouse till Heaven, connected to the Shechina and came back down. If he could so can I."
The man continued meditating and started flying high into the sky. He flew higher and higher into space, passed the milky way and continued flying. Then he remembered that Moshe Rabbeinu fasted and didn't sleep for forty days. Would he survive that too? He started worrying. Due to his worry, he lost a moment of concentration and meditation, so he started crashing back down. Now he was really worried, maybe he would miss the universe and continue straight into space. "Hashem, please save me," he begged, "please make sure I land on earth." Hashem listened to the prayer from a broken heart and fulfilled his request. Then he remembered that two thirds of the world is water. That's just what he needed now, to land in the middle of the Atlantic Ocean.
"Hashem, please have mercy and help me land on dry land." He looks down and sees Hashem answered his prayers and there is land below him. He continued to worry maybe he'll land in the desert. "Hashem, please return me to my house." Hashem fulfilled his request. He opened his eyes and found himself a step away from where he started.
Its only a parable, but what's the message?
We fly up on Rosh Hashana, continue on Yom Kippur and Succos and we land back down after Simchas Torah. We fly up on Pesach night by the Seder and land after Shevuos. But we've moved forward a step. We might not have moved forward very much but we definitely have had some sort of elevation that remains engraved in our hearts, those special moments of closeness, the memories of holiness that enveloped us, remain in our hearts. We're at least a step forward.
But even without that, there's another reason. What would our life be without any spirituality? How boring, how wasteful. For that we have the Passuk Vayehi Binso'a Ha'aron - and when the Aron began to travel. We have our spiritual journey. Why? To give a break between all our suffering and materialistic life. Without these special moments, how would we survive.
