Once again, this is not a “forgotten” or “ignored” technology, but it seems to me the writers of TNG and later series have never really come to terms with the socioeconomic implications of matter-replication technology and matter-energy conversion technology. If antimatter can be made out of matter and combined with it to produce energy, and if a replicator can make anything, then no material goods are in any way scarce any more – are they? Services and labor (such as the labor of programming the replicators) would be the only things of value on the market.
In one TNG episode, the Enterprise crew, in a side errand on their way to check out mysterious happenings in the Romulan Neutral Zone (ultimately blamed on the Borg, I believe), pick up three 20th-Century Americans who were found in a cryonic-suspension module drifting through space. (That the ship could have drifted across stellar distances in a few mere centuries was implausible, but never mind that.) At the end, on of the corpsicles, who was a millionaire in his time, complains that no trace of his money can be found. Picard replies, “This is the 24th Century. Material needs no longer exist.”
Yet in other plots it appears that material needs do exist and cause interpersonal conflicts, just as in our time. In one DS9 episode, Mog organizes Quark’s staff into a union and leads them on strike because, among other things, they’re not getting paid enough; so it appears money is something that is still valued, and the lack of it is keenly felt.
And there are merchants – especially the Ferengi – who take great risks and travel far to make money. And there are thieves and criminals, who do dangerous and illegal things to acquire money. So what’s the big deal about money?
Also, there are still wars. Civilizations with technology equivalent to the Federation’s go to war with it and with each other – ostensibly for control of territory and living space, but unless your home planet is really crowded cheek-to-jowl, any war for “living space” is really about control of resources, isn’t it? But nobody who has matter replicators really needs resources. Any matter can be converted to antimatter fuel. And since replicators apparently make matter out of energy directly (rather than, say, using nanobots to break down matter into constituent molecules and then put the molecules together in different arrangements), then presumably they can make any material substance – food, water, clothing, antibiotics, gold, dilithium crystals, gold-pressed latinum – in unlimited quantities. Everything anybody might think of as a material “resource” can be synthesized out of any kind of raw matter.
So what’s left to go to war for, or to go into commerce for, or to go on strike for?