I'm not disagreeing with your last point, but there was a drastic change in his demeanour at that point. He walked into Centre Court with his sleeves rolled up, chest puffed out, and looked as calm as any first time Wimbledon finalist has ever looked.
He'd demolished Fed in their US open semi and had match points the previous year. It's true that Federer was playing better, but I'm not sure that Cilic wouldn't have been secretly confident that he had a good chance if he got off to a good start.
To me, that 10-15 minute stretch where the match got away with him might have done him in. I have no way if knowing what happened there. None of us do. But the tournament doctor didn't work on him. It looked as if he had some sort of breakdown.
Perhaps - as Boris Becker said - because he was out there alone, down heavily after only 40 minutes played, and there was nowhere to hide. Tennis isn't like football, basketball, MAN, boxing,or any sport where a coach can "right the wrongs in your game plan or play. There aren't any timeouts. Theres no one to talk to. You're out there all alone,and it could have simply been that Cilic found himself isolated on centre court against a zoning Federer who was was giving him a beating in the final of the most pretigioius tournament in Tennis, with the etire world watching the drubbing and with no where to hide.
I can't be sure, but I suspect that might have lead to the capitulation.