Honestly the HK GMG is a fantastic piece of kit, even without a good FCS. It just gets range (or effective engagement range) limited with a good FCS and LRF.
It isn’t a 60mm Mortar though (and I’m not the biggest fan of those personally).
The issue is that while it makes sense to replace gear with newer equipment, it doesn’t make any sense to replace something with a different system that doesn’t fill the role the other had. Common sense should dictate that a 40mm Automatic Grenade Launcher is primarily a direct fire weapon, with low trajectory indirect fire possible in some circumstances.
I mean this isn’t a novel new concept, AGL’s came to be in Vietnam, and no one ran out and dumped mortars for those.
The same stupidity saw the Mortar platoons cut from the Infantry and assigned to the Artillery without any PY increase.
I don’t think anyone is going to argue that a 81mm Mortar isn’t a 105mm or 155mm Howitzer. But that is exactly what the Army did with the Mortars, as if a gun Det has a gun and a mortar, they can’t use both…