Why did Andy donate all of his toys to Bonnie at the end of Toy Story 3?

The toys want to play by kids again because if Andy puts them in the attic that no one will play with them. Or if Andy takes Woody to college that's not good because they will miss him. The toys want to play by kids but they should can play by themselves in the attic and Andy shouldn't give Woody away because he was from his father's toy that he gave Woody to Andy.