On such a holy, beautiful day, why do we recite a list of sins again and again?

Because one day of the year is not enough. We wish our souls to be united with her Beloved every day of the year.

So we read out loud through this list, and one by one, through G‑d’s great kindness and love for us, the stains on the clothing of our souls fade away. 

Then we rise higher, into a yet more intense light in which the stains can still be detected. And so we repeat the list again.

Until, by the end of Yom Kippur, we enter the new year in sparkling, fresh clothing for our souls. The essence-light of Yom Kippur may now shine within us for an entire year.