James Mortimer 21.Sep.2012Getty Images
Argentina has lost three and drawn one so far in the competition, but pushed the Springboks to the limit with a 16-16 draw in Mendoza, before coming close to shocking the Wallabies in the Gold Coast, losing 23-19.
The All Blacks great, speaking to Gulfnews.com, said that Argentina's inclusion also was developing the game, not just the 2007 Rugby World Cup third placed winners.
"Rugby needs innovation and we need to develop the game globally. Facing a different style of opposition will reinvigorate the competition," Marshall said.
However Marshall felt that the Pumas needed to develop a harsh edge if they were to win tests against the top three nations in the world.
"Argentina have lost matches they had been leading," he said.
"If they want to continue in this championship they need to be more ruthless."
Adding a sleeping giant like Argentina so far had worked wonders to the former Tri-Nations, but there was some questions being asked as to the future of Japan, with the kings of the Asian Five Nations beyond local opposition.
Their future in the Asian Five Nations is now under doubt.
Some have felt the issue doesn't lie with Japan, but in ensuring that other nations like Hong Kong, South Korea, Arabian Gulf and Sri Lanka continue to develop.
"It’s difficult (growing the game in Asia)," Marshall said.
"Teams in Asia below Japan need Japan but Japan doesn’t necessarily need them. In the meantime the Pacific Island nations can always provide Japan with a test.”
“The future is there for the taking now. If teams are developed enough to compete at this level and have a fan base that can pull in the ratings, everyone benefits.”