Want to know what I think?
In the last three successor wars, the CCAF had a lot of A4 left on platforms, but had to remove them due to not having enough ammo to support them in the field. They switched over to LRMs and used leftover mines from past productions. We know this because TPTB made House Liao famous for minefields, and gave them T-Aug rounds! They also are an Inferno user, so when the A4 came back, in this case the ability to produce ammo, CCAF production just seemed rational to put it back on everything possible.
TT