It's also the case that for the warfare that the U.S. fought during the 20th century FMJ bullets were much better bullets for warfare than any JHP or exposed lead bullets available, and for more reasons than price and durability, though those are valid reasons.
Simply put, the base reason we chose to "comply" and use FMJ bullets is reliability. (feeding). Nothing is more reliable feeding through semi and full auto weapons than FMJ. The soft points, "dum dums" and hollow points available for most of the 20th century simply don't feed as reliably as FMJ, and while a civilian might get his 1911 "throated" to feed hollowpoints, the military wasn't going there.
Dependable, reliable function from the stock designs in service was the important thing, and lower reliability even if it meant possibly greater effecctivness of the bullet was not an acceptable trade off.
Remember the two primary concerns of the military, about almost everything. Reliably able to do the mission, and cheap enough to fit the budget. Everything else is a lesser concern.