Blu-Ray beat HD-DVD because every PlayStation could play them. HD-DVD was arguably a better format, but better doesn't beat convenience and availability. You could buy a peripheral player to plug into your XBOX-360 but... come on. Who was going to do that.
Betamax was better quality than VHS. More robust, and smaller. But porn was only available on VHS, so game over.
MiniDisc was peerless. Smaller, more durable, and more versatile than CDs. It didn't matter though; people had already invested money into CD collections and the change wasn't big enough to make it worthwhile.
I wish I'd kept my MiniDisc player. The small inline remote with a screen, twist the end to change tracks, a small clip to go on a bag strap or jacket. Record music in mono to double the capacity, flip a small tab to prevent overwriting (a nice carryover from tapes).
OK, I'm off to eBay.