From a peak of 18 teams across four continents in 2017, including the Japan-based Sunwolves, Super Rugby has contracted this year to 11 teams in New Zealand, Australia and the Pacific islands.
Barrett has played in several manifestations of the competition, including a New Zealand-only competition enforced by the COVID pandemic in 2021, and wants a return to a greater geographic spread.
"It got tiresome when we were playing head to heads with just the New Zealand teams, that was not a great competition, to be fair," the Auckland Blues back told reporters at the launch of the 2025 Super Rugby Pacific on Wednesday.
"It is exciting playing Australian teams, travelling, having the (Fijian) Drua and Moana (Pasifika) involvement.
"I'd love to see the Japanese become part of the competition. I feel like we need to grow the competition and in that respect, that would be great."
Super Rugby featured 15 teams when Barrett made his debut for the Wellington Hurricanes in 2011 and it expanded to 18 with the additional involvement of Japan and Argentina in 2016.
A contraction back to 15 teams in 2018 was followed by the COVID pandemic, which effectively brought an end to South African involvement.
Barrett said it was important to make the competition more attractive to older players who might otherwise be tempted to take up lucrative contracts in the northern hemisphere.
"From a player point of view, we've lost South Africa. We need to grab another country and fill those spots so it creates a better competition," the two-time World Rugby Player of the Year added.
"It's the travelling, the experiences you have off the field, but also the stadiums, the different environments you play in, that's what makes you a good player.
"And it's those sorts of things that keep players who have been around a bit more interested and excited to get back up for another season," he added. "Otherwise it's the decision, 'okay, I'm getting a little bit stale. Let's go offshore'."
Unlike South Africa and to some extent Australia, New Zealand still only allow players based in the country to represent the All Blacks at Test level.
Barrett, who has had two lengthy sabbaticals in Japanese club rugby, thinks the policy should change for players who have already offered long service to New Zealand Rugby and believes an expanded Super Rugby might provide a framework to allow it.
"If you have Japanese-based Super Rugby teams, Australian-based Super Rugby teams, I think if there's Kiwis that want to go and play there, they can still be eligible," he said.
