The whole class of gallium nitride laser diodes have kind-of always been called "blue lasers". The gallium nitride system, as it stands now, is in commercial production of both violet and blue laser diodes. This may be just a language barrier thing, since the people who did all this first were Japanese, not native English-speakers.
So they had these "blue lasers" that were made of gallium nitride, and they kindof figured out which ones/which exact colors were easiest to make (or easiest to make reliable, powerful, and least costly). I don't know the whole story about how this came about and who "decided" what would be the standard at what point in time, but violet is what got decided upon. It's probably a combination of easiest to make, lowest wavelength (since the lower the wavelength, the more info on a disk), but not too low of a wavelength (maybe there's a reason they didn't want to go into UV? Maybe a property of the disks themselves? Not sure), and cheapest to make.
But they've always been called "blue lasers" in many circles. The first gallium nitride laser made lased at around 400nm, definitely violet, but the book written about the subject by the creator of the thing is titled "The Blue Laser Diode: The Complete Story". So the name for the whole class has kindof just always been there.
And, it's all marketing to Sony. If they thought they could sell more products with the name "Fish-Ray", I'm sure it would have been named Fish-Ray.