There is a line of thought that says that assassination is one of the most humane mechanisms of political/social change. Only one man dies.
There is a line of obsrvation that says the usual conesquence of an assassination is either 1) nothing specific - next guy steps up and takes over, hard to say what the change was (Lincoln, Kennedy, Malcolm X, that one Prime Minister of Inda) 2) bloodbath, as factions move into the power vacuum.
The problem is guiding the change. As a mechanism, it has no steering wheel, or brakes.
Thought experiment: France assassinates Hitler in '36. Consequences: maybe 1) sanity takes over the German government, which demilitarizes apologises to the Jews and remains peaceful to this day, or maybe 2) the new leader gains power from Hitler's martyrdom, launches better planned and more sensible war, establishes a homeland for expelled Jews in France rather than killing them, forms a stronger alliance with Stalin including the mutual development of atomic weapons (both Soviet and German Jews allowed to occupy French homeland, do science there), leaves England alone, cooperates with Soviets and Japanese in dividing China and SE Asia, Soviets and Reich and US settle into three way nuclear and economic standoff or maybe 3) something else.
These are all very complicated considerations to take into account each time. The temptation toward impatience, not thinking, is great. So we have morals and ethics to prevent us from bothering with such error-prone arguments. Assassination is wrong, we know that, we've figured out why long ago and don't have to go over it each time it comes up.
