The idea of volley fire basically disappeared in the late 1860's to early 1870s. The US Civil war saw some of the last major uses of it in battle. The main reason for it disappearance is due to technology. Volley fire was seen as an effective way to maximize firepower with the use of single shot muskets. However, the proliferation of breechloading, and eventually repeating rifles becoming the norm in the 1880s, killed off the idea for good. Rifles were not only more accurate but a single man could put more rounds down range than ever before.

Accuracy meant it wasnt cost effective for men to just stand in the open. The Franco-Prussian war of 1870-71 also serves as a perfect example of what was to come with artillery. French battalion formations were easy pickings for the German artillery which had become more powerful and accurate. It was better for men to be loosely spaced to not all be wiped out by artillery and their lose spacing would have less effect on their firepower potential as each man could provide the fire of multiple men. Instances still exist of larger formation tactics being used still, such as the British in the Boer war who were cut down by the Boer guerrillas shooting them from concealed positions as the British advanced in larger groups.

So long story short, the combination of better small arms for the regular soldier and the ever increasing danger presented by artillery meant looser formations were key to avoiding mass casualties by men just standing in the open.