The Army has decided to switch because they know that it is better to be prepared for a war that never happens then to let it happen.The Army wants the budget to fight WWIII, they don’t actually want to fight it. More importantly, neither does Congress. And going to a bulkier, more volumetric round before you go poking the bear and the dragon is the kind of pants on head stupid that only big army is capable of.
We don't want another Pearl Harbor or 9/11.
The Army is planning to make life easier with a lighter and more powerful LMG, and a more powerful round in the NGSW.
Hell, there is talk of making a lighter M240 but in 303.
The Army is changing to go inline with modern warfare