There’s no happy ending ... Nevertheless, we might well say that is exactly Harriet Beecher Stowe’s point. In 1852 slavery had not been abolished. Slaves were still on the plantations and many of them were in the hands of people like Legree. Her book was written to shame the collective conscience of America into action against an atrocity which was still continuing. So a happy ending would have been, frankly, a lie and a betrayal. ...Shippey only had a half hour discussion of Uncle Tom as a hero and so he glossed over some of the things with which one could take issue in his statement. For example, I'd say that Stowe was trying to provide a role model for all of us, often in the slaves she wrote about, but you have to look at it with a Christian focus to see that clearly.
Most of the charges are basically true. Stowe did stereotype. She did sentimentalize. She offered a role model which later offended African American pride. On the other hand, what she did worked. She wasn’t trying to provide a role model for African Americans. She was trying to make white Americans ashamed of themselves. ...
Perhaps the short answer to her critics is to ask, “Do you want glory, approval, all those good things? Or do you want to achieve your goal?”
Thomas A. Shippey, Heroes and Legends
That aside, I love his defense because I love the book so much. Without context it is easy to cast stones at anyone. And we're all in that glass house where we don't want the stones cast back at us. Our lives and viewpoints have context which we'd like understood also before we are judged.