Muscle mass does not equal=healthy. Jay Cutler or Ronnie Coleman are not the peak of health. It's based strictly on what's healthiest, not American's ideal body image.
Have you seen a Coleman video? That guy takes 60+ pills a day and most of them are prescriptions. I don't care what anyone says, the guy isn't healthy.
I have to disagree little to your post, muscle mass does equal healthy, but only to an extent. Someone that is 5'10" and shredded at 280lbs is probably not healthy. Someone that has visible muscle and not too much fat is probably healthy.
As far as America's ideal body image, Coleman and Cutler are far from it. Bodybuilders haven't been considered mainstream since the 90s, and most of them are referred to as freaks instead of having ideal body images. Aesthetics appeal left bodybuilding long ago and was replaced by un-human width and muscle mass.
??? I don't consider myself fit... can't run a mile without feeling like i'm dying. 6'4" tall and weigh 220 with a 37" waist. However, my cholesterol is 135, perfect blood pressure, perfect everything else. I'm perfectly healthy, but not fit.