Rey. After witnessing what his dreams were built on and what he would be supporting if he ran away and tried to hide from the first order, he decided to stay and fight.

I get why people don't like the scene because they hate Rose and they don't like that the events there didn't impact the events of the movie but if you think about it critically you can understand why it's there and important.

It was also needed to show Poe that even the best laid plans fail and that flying by the seat of your pants doesn't always work. His plan got a good chunk of the resistance killed because DJ gave them up