I figured they would be cutting edge. I still think FMD-ROM is going to be very cool. I've used optical drives frequently. They are niche hardware mostly used for log files, transaction files, etc. If you want to see state of the art optical equipment, visit a credit card processing facility.
Every transaction is stored on optical media.
Being replaceable is both a strength and a weakness - they lack the very high data density that magnetic media has. Each row contained 2 power supplies and 16 drives. I think there were 7 rows of drives per rack. It may have been the reverse - 16 rows of 7 drives. The drives had a much smaller capacity than today's disks.