It’s about safety and cost when it comes to data storage… yes shorter wavelength emission/reading systems are possible but are they necessary. At the moment we are yet to have a video encoding system that needs a disc bigger than 128GB for a movie. Chances are by the time we do it will be streamed via the internet and a physical disc will be redundant.

But who knows what future tv formats will need for storage, when I was a kid a 240line VHS tape was astounding now 1080 lines is considered old technology.