You can rephrase it all you like it doesn’t change the question: why would the US spend a bunch of money on artillery ammunition when it and its NATO allies don’t use artillery? Why waste money on something we don’t use?
The US armed forces make a lot of dumb choices with their funding but “underspending on artillery we don’t use” is not one of them. Even with hindsight it doesn’t make sense.
Plenty of M-777 M-119s and M-109s are still in use. The idea that the US doesn't have or use artillery is just factually wrong. The fact we didn't have substantially more ammunition stocks for those weapons is a mistake.
Rephrase: No one expected a real land war in Europe without establishing air superiority.