Artillery & surprise attacks or ambushes are my thoughts.
The M1128, as is, has only 18 rounds aboard but has space for 5 dismounts ... Another invisible RAMs mod will be to increase the ammo capacity & nix the dismounts.
Still, I probably can't expect it to carry more than about 24-26 rounds in an expanded carousel.
Therefore, like the real deal, ammunition will be at a premium & only available for suitable targets for the 105mm.
So, unless there are concentrations of enemy foot-mobiles or light vehicles, the big gun is for AFVs, bunkers & loosening up barriers for the ESV. They have the 30mm's on the M1296s for the lighter stuff.
PS: I guess the Stryker teams never had to deal with much in the way of artillery in Iraq or Afghanistan, & there was no real need for serious anti-AFV work, so they could fire off their ammo, retire & re-arm, & return. Something which may not be possible in a peer/near-peer conflict.