Back's pretty important for Mr O. Glute and ham conditioning is also a big deal for judges as it indicates overall conditioning and is the hardest place to lose fat and water.
You're right about delts and traps, but chest....no way does Kevin have a better chest. Also, are you claiming from those pics that Kevin has bigger calves? WTF? He has no calves at all. Way smaller/worse quads. Legs and back make up about 2/3 of the muscle on your body. Ronnie clearly has massive triceps, although his biceps are more of a standout bodypart yes. You don't get 22-23 inch arms with no triceps.
Aesthetics goes to Kevin, but as Branch Warren says, there's another word for "aesthetics", SMALL haha. Bob Paris never won Mr Olympia, although he looked great. Flea Labrada never beat Haney to Mr O. Kevin is smaller everywhere except maybe delts, since Ronnie's traps from the back are still bigger. Is this a bodybuildong competition or a pretty boy contest?
I've now included a pic from the front to this effect.