I disagree. We're not the Uncle Toms, and if they want to throw it back at us, let 'em. I think it's about time we had that dialog. ,P>The fact that we stop being afraid of it and use it with its right meaning is very powerful.
Plus, what is the original or "right" use of the phrase? Neither your definition nor the one you condemn would have been shared by Harriet Beecher Stowe back in the 1850s. She thought she was creating a strong positive character.
Strangely, in spite of the way the phrase is thrown around lately, Wikipedia takes what might be Stowe's positive view of Uncle Tom. I doubt they'll change the way things are now.