When Minidisc was announced I thought it would be a perfect removable storage solution; at the time people were using Syquest drives for "large" (44 and 88 MB) removable storage, and they were pricy; there was a market waiting for something cheaper yet still reasonably fast. I think a Minidisc could hold 250MB or something like that - good storage at the time, relatively cheap, and would probably have been pretty reliable.
However, Sony's anti-piracy worries made Minidisc inaccessible digitally - there were no Minidisc readers/writers and you could only use it for recording/playback of ANALOG audio!
Soon Iomega came out with the very popular 100MB ZIP drives and Sony's window of opportunity closed - and we got to enjoy crappy Iomega quality and the infamous "Click-of Death".
Sony does come out with cool tech sometimes, but their entertainment division screws it up every time. I guess Sony made their money from Minidisc, but they could have done so much more with it.