The opening lines of Nier Automata are nihilistic and signal 2B’s desire to just get death over with. Nothing in the whole game’s story brought this feeling back in the other direction, and as a result of an adventure spanning a gray and brown “Abandoned city and death” the optimistic ending absolutely didn’t hit with me. Hard to identify why my response was so different from everyone else’s.

Yoko Taro let the answer to the player, even in the good ending is for you to decide why is worth living.

spoiler

If you find the 2B flight unit you can read the message she left for 9S. “The time I was able to spend with you It was like memories of pure light”. To me this message is 2B answer for the question of what is worth living. Another thing, the OST for the main area of the earth, the cozy ost, is named Rays of light(I think is the same name in japanese) and to me is referencing the “memories of pure light”