Japan beat the hosts 1-0 in the final to win the title for the third time in the last four editions, with Maika Hamano scoring the decisive goal.
Australia's victory over North Korea in the quarter-finals secured their spot at the World Cup in Brazil and Kerr said there were many positives to take from their Asian Cup campaign.
"We qualified for the World Cup, which is a positive and Japan are a great team," Kerr said in Kenya, where Australia are taking part in the FIFA Series friendlies.
"Still haven't fully reflected on it yet as it was really disappointing, feel like a big opportunity missed. But I feel like with what we achieved, and how the nation got behind us, it felt like a positive tournament.
"It's important, just in the fact that you're going to face different teams in the World Cup," the Chelsea striker added.
"The World Cup is getting bigger each time, and you face different teams from all different confederations, so it's important for us to be ready for all types of games."
Australia face Malawi on Saturday before taking on either Kenya or India.