Why the hell not? We certainly judge 1940's notions of bigotry and prejudice by today's standards.
I think you are comparing apples and oranges. At the time Rosemary was giving a lobotomy it considered medical cutting edge treatment. The doctor who performed the operation had promised the family the treatment would help control their daughter's mood swings. It was not until later it was discovered the treatment was not the miracle it was thought to be. It is a lot like our current enchantment with Prozac and drugs of the type. It is only now several years later that people are asking questions as to their safety. After Rosemary was damaged by the treatment what was the family to do? They could not undo the damage. They put her someplace where she could be cared for since her mind was basically gone. It is a sad story. I dislike the Kennedy as much as most other FR members but in this case I think the family made a very sad mistakes based on unsound medical advice.