The Greeks believed that humans were what mattered most. Greeks originated humanism, which is basically the idea that human interests and ideas are what are most important. Because of this mindset, the Greeks determined that humans were the measure of all things, including art. The way that they portrayed the human body was godlike. In almost all Greek art, the human body is shown to be completely flawless and absolutely perfect. The sculptures show men who are muscular and defined representing what the Greeks thought was the "perfect" form. They believed that only the perfection they portrayed through their art was what was beautiful and that is what the Greeks strived for.
In today's society, we strive for the "perfect" figure as well because that is what the media, magazines, books, and people tell us is beautiful. This idea of "perfection" is advertised everywhere too. We see pictures of men and women who have the ideal perfect bodies in magazines, on television, and on posters. Because of what our society has deemed to be ideal, that is the perfection that people try to strive for.
I am not really sure if human perfection was first started by the Greeks, but their art is what made it famous. And that idea of bodily perfection is still acknowledged today in just about everything. Society tells us that if you are not skinny or muscular, then you do not have the perfect body. Greek art may have been created in order to promote only what their society thought every person should look like.