We talk about the MiniDisc a lot over on Stereo2go.com The format should have taken over the world but it never lived up to expectations. They even "relaunched" it in 86 but it stll didn't get a foot-hold. In my little part of the world it was way too expensive, players were several hundred dollars and blank discs were 3-5x more than cassettes, usually as much as a pre-recorded CD.
The other problem, very similar to stereo microcassette, is that you also had to get a home component deck and car stereo to have the full ecosystem so just jumping in, recording your albums and playing them on the go, was close to a thousand bucks. With all of it's faults, as with most modern vintage audio it's getting really collectable. They loved the format in Japan and they cranked out a million different little players, some extremely nice, some very basic. Prerecorded discs go for silly money now.
I've got several players and component decks, one is a TOTL Denon used at radio stations, I guess they loved the format for commercials and talk radio? Mine even had a talk radio program on it and some other goodies, unfortunately I only got one disc with it.
MiniDisc also had other applications, it's basically an extension of the floppy disc, they had a data drive set up for computers and also for portable video/cameras.