Most people find symetry and proper proportions to be attractive. Lyoto definitely has some of the characteristics. To put it the way my wife just said it "he certainly isn't bad looking".
Plus that is kind of a bad picture of machida. Looks like he just finished a workout. He looks way more badass here:
^^^ Hah!!!! Love it.
I read an interesting article about how symmetry produces better athletes. It makes sense.
I've been obsessed with muscle symmetry / posture etc ever since. One of the reasons I constantly switch between regular stance and south paw I suppose.