I don't know why he did that interview.
If he said he was "over it," nobody would have believed him.
By saying he's "not over it," he makes it easier for his players to continue dwelling on it.
Makes me appreciate even more the genius of Bill Belichick when he said, "We're on to Cincinnati."
It would have been a totally different answer if Quinn had said something like: "That was a tough way to lose any football game, let alone a Super Bowl, but we're on to next season."
If asked, "But are you over it?" he could just have said, "We're on to next season."
If asked, "But what did you learn from the loss?" he could have said, "Everyone, players and coaches alike, have a lot to learn from the great season we had as well as from that game."
Oh Good God! I've been listening to Belichick too long!