If this is a points advance reservation, and you haven't actually paid any points yet, why would you book non-refundable flights before you confirmed your stays?

Anyway, if you technically haven't paid any points from your Marriott account for this reservation, I don't think you have much grounds to complain here.
Though it's still Marriott's fault to overbook then cancel a confirmed reservation, the most you can do now is request points to credit to you for your inconvenience, or get the property to change your dates for another stay. I'm sure they can work around to a future date up to 12 months out from now.