Most murder victims are not killed because they are good.
And any reasonable homicide investigation begins with, "who wanted to kill him", which usually leads directly to the dark side of the victim.
I wrote this in 1994:
Most of the researchers theories of which I am aware about the motive for the crime can be summarized as: "JFK was killed because he was good" (insert your preferred goodness here: Getting us out of Vietnam, opposing the Federal Reserve, wanting peace with Cuba/USSR, prosecuting the Mafia, etc). Of course, there was obvious government participation in the immediate aftermath of the crime, and also probably in the crime itself, AND the participants have kept their secret for 34 years.
This requires that you believe that many actors had motive not just to do the crime, and not just to cover it up, but to sustain the coverup for a generation. Now, I find it implausible that so many people would be able to sustain such an incredible effort for so long UNLESS THEY BELIEVED THAT THEY WERE DOING THE RIGHT THING. The person who cracks this crime will be famous and also have material rewards. There is a major incentive to tell the truth now, and none to lie, unless there is an underground story or legend WHICH REMAINS PERSUASIVE TODAY about why the coverup should continue.
When a normal person is killed unexpectedly, the search for a motive begins not with the victim's good points, but with the passions and behaviors which might have brought another person to commit homicide. This search for a motive often reveals new and unanticipated facts about the victim. Such facts about JFK may be available now, or may appear in future books and papers.
It is my own view that JFK was caught in a vortex of his own making, of aggressive anti-Communism, secret operations involving extralegal and extraconstitutional use of force, and his personal life. These were his passions: (Pay any price, bear any burden, Green Berets, covert ops, compulsive sexual behavior, undermine the institutions by numerous back-channel connections to lower-echelon types not afraid to take chances, etc.) If you were, say, Hoover, and you wanted him dead, how easy it would have been to make up a story (and how much easier if the story were true) for Allen Dulles, or others, that JFK had been sexually compromised (or pick another vice of your choice) by a Russian agent, and that the secret deal not to invade Cuba was the result. An impeachment trial, so the story would go, would leave the country weak and defenseless at a time when almost everyone, not just a few nuts, thought the reds were scaling the walls (Cuba, Berlin, Laos, duck and cover in my fifth grade class, etc). In order to save the nation the agony of a treason trial in the Senate, why not let a few good men take care of the problem in a way which will leave a dead hero.
The virtue of this scenario is that it provides the remaining actors who are still alive just as much reason to keep quiet today as in 1963.