The former Selecao international says the striker has made the right choice in deciding to snub the country of his birth as he wouldn't have been guaranteed to play anyway
The Atletico Madrid striker was born in Lagarto but has made Spain his adopted home after moving to los Colchoneros in 2007.
Costa represented Brazil in a friendly against Italy in March 2013 but then caused uproar by deciding to play for la Roja having been granted Spanish citizenship last summer.
But, while the Selecao originally contested the 25-year-old's surprise move, former Brazil international Edmilson says his nation were right to not take their protests any further because of the quality at their disposal.
He told AS: "It's not an error to have acted how they've acted. He's a player who wants to wear a different shirt. I think we've got players who are more ready than Diego right now. We have better players than him.
"There are players in Brazil who can cover his absence. The decision when a World Cup is approaching is always difficult. But for me it is very clear.
"He's having a great season with Atletico Madrid. In Brazil he wasn't that well-known, and all his success has come whilst he has been in Spain. I think the decision he took was the right one. He earned his name in Spain, knows more people, his children are growing up there.
"The moment wasn't right for Diego Costa. If this has happened 18 months ago, the picking of a player who isn't too well known in Brazil, it would have been strange. We've got Fred, Luis Fabiano, Jo and Alan Kardec,
"It's not about Diego Costa's quality, it's about the right moment. There are players who are more prepared and integrated right now with the Seleçao."
Costa is set to make his first outing for Spain when they face Italy in an international friendly at the Santiago Bernabeu on Wednesday.