The first and most visible potential benefit is cost saving. If two, three, or four nations decide to procure some kind of equipment together and if they can avoid having national specifications that add to the common foundation of the procurement program, then they will save money and time. Knowing that defence budgets are very restricted, it will enable the same nations to continue maintaining capabilities in other fields or develop new ones if they think they have to face new missions and new challenges.
On May 3rd, 2012. See this statement in context.