It is not just that people want free will, it is that most people believe that we have it.
Whether we were made by a supremely all-powerful being or we evolved to be what we are from a single-celled organism in the primeval swamps, we have analytical brains which take in information and process it to work out the best way to proceed, within the limits of our environment and the moral and/or social mores we have absorbed.
If God made us "in his own image" then he must have programmed in that ability, and chosen it from his own characteristics as something which we should have. You don't design a robot with qualities that it is not at liberty to use. Not to use it would be waste and ingratitude.
If we are the descendants of a tiny green blob, that is pretty good going, and we should not squander our progress by abandoning ourselves to the vagaries of chance, or the coding of a master programmer.
(I am proud of my upwardly mobile green-blob ancestors, BTW)