It is not that small considering how well NAS is doing in the pro / consumer market.

The problem is BluRay capacity is too low. Had it been 1TB per Disc it might stand a chance. But using 40 disc just isn't something prosumer is willing to stomach.

Not to mention both Tape and Optical Disc aren't that durable. I just read Walterbright, the author of D programming language had to throw away his code because of inadequate backup solution at the time. We dont need to store and save every video, but there are things that is worth saving. And I wish we have better solutions.