I'd hope not. Deleting a Facebook account shouldn't delete all of the messages sent from it from their receivers' inboxes -- what if a long time friend decided to delete there Facebook profile? I could lose years worth of conversation with them. Messages belong as much to the receiver as the sender, if not more.
I hope you are backing up up those things. If you don't, you should have zero trust into being able to access those even tomorrow. Why would a company like Facebook care about you?
You feel like your memories belong into your control, then why do you give a third-party total control over them?
I'd hope not. Deleting a Facebook account shouldn't delete all of the messages sent from it from their receivers' inboxes -- what if a long time friend decided to delete there Facebook profile? I could lose years worth of conversation with them. Messages belong as much to the receiver as the sender, if not more.