You haven't noticed that they are constantly ridiculed, besmirched, considered guilty, given as examples of 'evil', 'murderers', and all sorts of other negative things? Maybe you would like to go through live with a very large percentage of the population thinking this of you in spite of being found 'legally' innocent?
Some accusations carry such a high degree of prejudice and hatred with them that the accusation alone will destroy a persons life almost as much as being convicted, even if he's totally innocent. I've seen it happen to people.