A useful illusion of Free Will is that we can to some degree predict the future state of the world and influence the future state of the world. To make meaningful agent type activity you have to have a world full of causality, in other words --- and to have causality it is awfully nice to have some deterministic properties (or science might not work out so well). So! I for one am a hard-compatiblist. I think that not only is "useful free-will" aka Agency compatible with determinism, I think that determinism is necessary!

(concepts probably stolen or bad copies of Daniel Dennett models)