Two huge factors were firearms taking the dominant role on the battlefield and the industrial revolution. At the same time that you see bladed weapons going very utilitarian and more like cheap trinkets, you see firearms getting all that attention in the way of embellishment and improvement. For 3,000 years the Bladesmith was the wizard of weaponry and the cutting edge of metallurgy. But when those boom sticks caught on, metallurgy focused more on creating metal cylinders that could handle the pressure of a powder charge. The bladesmith's services were no longer required and he was relegated to making outdated curiosities, soon the specialty was absorbed by general blacksmiths and you see the frontier style blacksmith knives that were dominant on colonial frontiers. The final nail on the coffin was when mass production rendered custom, hand-crafted blades a silly notion for a nonessential trinket. Sheffield did a fair job but they were still lesser facsimiles destined for wall hanging rather than the grand weapons of old.
One exception that I have often taken with groups like say the ABS is the claim to preserve the art of the forged blade while focusing so heavily on the efforts of 19th century blacksmiths, who were merely trying to emulate the true bladesmiths of old. This is the basis for my fascination with the much older blades, they are from the time when the Bladesmith was a true force to be reckoned with, and much of that incredible tradition has been forgotten.