ACME pins are produced by the company ACME Archives which has a license to produce official Disney artwork and pins. They still have to be ok'd by Disney. If I remember, there was in fact an ACME store at Shanghai and/or Hong Kong Disneyland, but it closed? I've known about them for years before the pins came out for producing limited edition paintings, prints, giclee's and so on.
A licensed pin is just as much an official Disney pin as any other. They just do not have that"Official Disney Pin Trading" logo on the pins. They still have to submit the designs to Disney for approval, or go through some sort of process to get made.
No they're still not the same as fantasy pins. Fantasy pins are made by people with no affiliation to the Disney company, no license to produce, no agreement, no contract. Fantasy pins are also technically illegal as has come up many times in other topics. ACME pins are just as much Disney pins as anything coming out of Box Lunch, or Hot Topic. Those for example are licensed by Disney through LoungeFly. They're still desired, and still just as much official Disney pins.
Some people may not care for them, for any number of reasons, but I'm sure there are still plenty of others who do want them.
Any enamel pin with a (c) Disney on the back is tradable in the parks with CMs.
Hope this helps.