Actually the price per TB isn't all that bad to have that much storage packed in one spot. Now sure as hell wouldn't just buy one. You would have to buy two or three of them so that you can have a backup of your data as well as no HDD comes close to that either. But if say speed isn't the reason. If it was used for a backup device, or on the consumer side i could see this being a media storage drive for like a Plex server or something where 400+MBps should be more than enough even for a few streams, you have to think.
4TB SSD is one of the largest consumer SSD's. You would need 25 of them to equal to one of these.
40K vs 15.5K on 25 4T SSDs, but then you would need one VERY large controller or a controller with SAS expanderas and the space and power for 25 SSD's where this one guy can do it. So yea for 2.5 Times the price, to have that one drive take up the power of probably a few ssd's and the space of what? a 3.5 inch drive.