When Jonas decides to leave, he knows that his community will go through big changes. He chooses to release the memories anyway, because he feels that his people should live a life of feeling, with both emotions: pain and joy.
The pros of change for Jonas’s community include the ability to choose, and the ability to feel emotions. People do not get to make their own choices, but if they had access to the memories and understood that things could be different, they would want to make choices. People would also begin to experience emotions. These emotions would include negative emotions like pain and discomfort, but it would be worth it for the positive memories of happiness.
The main cons of adding memories would be the confusion that would strike the community when the memories would return, likely to last a long time. Other disadvantages would include the negative societal impacts, such as poverty due to overpopulation if people have their own children, and economic hardship if job choices and housing are no longer controlled.