Optical media is increasingly niche. More and more content is delivered digitally and then moved around by flash. Also more and more content is being consumed on tablets and other devices which can't practically be built to read optical media.
What's the market now? I get that sneakernet can be faster than internet and that some people have restrictive bandwidth caps, but it seems like this would be increasingly moving towards just being an archive format. The discs are probably cheap and long lived, but I don't see them as being used for even a fraction as many applications as DVD.