Except Robespierre voted to abolish the death penalty before the rise of the jacobins, and was largely anti-violent until it was deemed necessary (which it was). France was on the verge of collapse from external forces (and not a lie that people like Stalin used to justify mass purges). Not only that but the jacobins had the popular support of the poor and working people at the time. Not saying the general public is always right, but it's not as if the jacobins were some isolated despotic group that nobody liked.
The "terror" was a necessary, justified, and in some ways moral event. The terror is not separate from the revolution, it's part of the whole package. If the goals of the revolution were just (and they were), then any methods used to get there must be considered. This is just logical, to say the terror shouldn't have occurred is to say the revolution shouldn't have occurred. It's the same with the abolition of slavery, you can't say John Brown was wrong for attempting to murder slave owners, or that the civil war wasn't worth fighting for. If you do you're on the wrong side of history as far as I'm concerned.
I don't agree with all of his policies, but the blanket negative portrayal (not necessarily by you, just saying people in general) is obviously disingenuous. He was a much more moral and principled man than the aristocrats, and the totalitarian nature of the monarchy lasted for much longer, and was more devastating to the people than the terror. For some reason liberals love to defend principles of liberty, equality, etc. but squirm at what was required (not just in France, but all over) to acquire/defend those ideals in the first place.
