Yo georgie, I have a really bad habit of reading what people write and responding accordingly. Now I understand from your subsequent posts that you have a Ted Kennedy bashing agenda, but read your original post one more time; 

"Why did Americans let Ted Kennedy off the hook for the Death of Mary Jo Kopechne?"

My answer to this question remains unchanged. Americans, only in the form of the state of Massachucsets justice system decided the penalty for Kennedy's actions and that's the answer to your question. 

Now, if you want to know what others, think about this why don't you ask this question. You might even get some to agree with you and I might even be just one of those. To infer that readers understand that you're seeking a Kennedy bashing forum from your original post is expecting too much. Here's my suggestion, re-list this question nd word it something like this;

What do you think of Ted Kennedy getting off the hook after causing the death of Mary Jo Kopechne?

You might actually get some of the responses you were looking for by asking the question in a format designed to provide you with that type answer.