The reasons why this topic will never go away are because 1.) no one was ever convicted, 2.) the President's body was not treated as homicide victim's normally are, and 3.) the official account is so improbable on the face of it that it defies credibility. Alternative theories or accounts [although they might lack evidence] appear to the public as having more plausibility.
One of the things I like to think I've learned about life is that sometimes very improbable things happen. Sometimes coincidences occur, and sometimes strings of improbable events occur.
However, I don't think the Kennedy killing is one of those highly improbable strings of events. My personal exposure to the darker side of government life [including the subject of assassination] leaves me inclined to conclude that the Kennedy killing was directed from within the government. This conclusion is not based on the volumes of theory, and their various details [much of which I disagree with] but is based on two things, 1.) my experiences with government figures of that era informing me that such a thing was within the range of their inclinations and abilities, and 2.) my strong conclusion that such figures were highly motivated to undertake an action as grave as that.
This latter factor is now discussed, in detail, for the first time in the book,
JFK and the Unspeakable: Why He Died & Why it Matters
by James W. Douglass.
Of this work Danny Ellsberg [formerly of MIT] writes,
"Douglass presents, brilliantly, an unfamiliar yet thoroughly convincing account of a series of creditable decisions of John F. Kennedy - at odds with his initial Cold War stance - that earned him the secret distrust and hatred of hard-liners among the Joint Chiefs of Staff and the CIA."
If there is any "key" to understanding the topic of conspiracy in this it is to be found in the profound motives of the possible conspirators, not in the technical issues. The technical circumstances, IMHO, are consistent
with a conspiracy, but they may also be consistent with a string of improbable events. By themselves they are not conclusive.