I think part of the problem is that computer 'airbrushing' is a lot cheaper and more realisitic that the old fashioned equivilent (when they literally airbrushed the photo). It is harder to spot as having been done unless you are good at looking for the signs and most of us don't bother to analyse every photo we see.

BTW, my avatar has not been airbrushed. Not even to remove the embarressing part which is visible if you look closely It is a good photo of me, though. In that position I have the illusion of musculature when really I am not as well toned as all that

I remember reading an interesting idea about evolution involving the natural development of most species being a divergence into 'robust' and 'gracile' forms which then develop into seperate species. It happened to elephants and to apes and it could now be happening to us (again, since we were the gracile form of the apes we descended from). The general pattern seems to be that the gracile form is more aggressive while the robust form is more passive and often vegetarian.