Barnes backs Becks' non-pick.
Beckham revealed in a statement released yesterday that Stuart Pearce, the head coach, had opted against picking him as one of his three over-age players.
Craig Bellamy, Ryan Giggs and Micah Richards are understood to be the trio of senior players favoured by Pearce.
Beckham played a valuable ambassadorial role in bringing the Games to London, but Barnes insists sentiment is irrelevant.
Instead Barnes, who won 79 caps between 1983 and 1995, believes the 37-year-old LA Galaxy midfielder is simply not good enough to make the squad.
"If you look at it from the point of view of winning the Olympics, then Stuart will know what he wants from his team," Barnes said.
"David's been a fantastic ambassador and a great player, but if you're only allowed three overage players, then Craig Bellamy, Ryan Giggs and Micah Richards would warrant their place more than him.
"From a political point of view given the role he played in bringing the Olympics here, it would be great had he been there.
"But as a coach you have to pick the best squad that will enable you to win and that's why Stuart has made that decision.
"The Olympics is about winning and you're belittling that if you say let's throw a spectacle by picking someone more popular. That belittles the Olympic ideal of excellence.
"It's supposed to be about the pinnacle of someone's career. You have to pick the best team."
NO OLYMPICS Beckham