He sure did have huge causes. He and his brother did more than anyone to cause the mess Vietnam became. As AG he spied on MLK at the height of the civil rights struggle.
I guess Richard Cohen forgot the facts of the reason for Kennedy's assassination:
Sirhan "Sirhan believed he was deliberately betrayed by Kennedy's support for Israel in the June 1967 Six-Day War, which had begun exactly one year to the day before the assassination. During a search of Sirhan's apartment after his arrest, a spiral-bound notebook was found containing a diary entry which demonstrated that his anger had gradually fixated on Robert Kennedy, who had promised to send 50 fighter jets to Israel if he were elected president."
JFK’s blundering diplomacy in Laos left the path open for Viet Minh supplies to flow to the south along the Ho Chi Minh trail. Except for the Cuban crisis, The Soviets played him like a fiddle. He was left with going to IKE at Gettysburg to get advice about what to do. If Ike, or even Nixon had been President, there would have been no mess in Vietnam.