The group had become especially contentious after including Indonesia in 2015, which had clashed with United Liberation Movement for West Papua, which holds observer status.
In an interview with Australian think-tank the Development Policy Centre, Ralph Regenvanu, said the MSG was disappointing and becoming less relevant.
"That consensus approach to decision making is failing in the MSG. Vanuatu's been consistently saying that it's not happy with the way that decisions are made, that they're not made in the consensus manner, and that's continuing."
Mr Regenvanu said if the group returns to its purpose it could become relevant again.