The Word 'Terrorist'

I think we should not call the Parisian murderers "terrorists". The term itself is odd because hides the fact that most of today's terrorists are cold-blooded murderers.
The word originates in the French "Reign of Terror" (La Terreur) conducted by Robespierre, and originally referred to the emperor and his terrifying suppression of the French people. During the Russian Revolutions Leon Trotsky used it essentially the same way.
It is a special word in the English language that implies the motivation for murder: to terrify with the very threat of it. We do not have a word for those who murder to commit robbery, murder out of rage, murder out of jealousy, etc. Why use a word that merely reflects the goals of those who purpose is to scare us?
Assassin is the only other special word for "murderer" that I know of, but it is defined in terms of the victim, someone of high social status. But it tells us nothing of the motivation of the killer.
The word itself is ambiguous. To the perpetrators of terrorism, they are heros, patriots, the chosen of God. Only the victims and those unaffected see it as an evil. Why use an ambiguous word when we can use an unambiguous one? Let's not give one set of murderers the succor of hiding behind a word they like, when we can give them no quarter with an unambiguous one?
Terrorists themselves hide behind this word, because it does not even imply murder. Religious terrorist think they are carrying out the will of God. it gives them carte blanche to do as much evil as they can. I can see the reason for the classification, but not for the use of the word in our every day conversations. The usage of it fulfills its mission: to scare people more than the simple word "murderer".