I think that maybe there aren't more primary blue instruments out there, is because there isn't much of a demand for the. Fender has made 5 shades of blue that I can think of: Sonic, Daphne, Aqua Marine, Lake Placid, and Ice Blue Met. No primary or vivid blue.
If an instrument is made with good looking wood, it will be displayed. Natural, White or Butterscotch Blonde, Sunburst, or a transparent finish of some type.
On rare occasions, Fender, for instance, has made (Grafitti) Yellow and (Competition?) Orange.
I think the reason, (at least partially) is that certain colors simply don't look dramatic under stage lighting. Black, White, Sunburst, Red, they look good under stage lighting. What color clothes do most people usually wear on stage? Black, white, maybe red, and their pants, black or Denim blue.
Vivid Blue, Grafitti Yellow and Competition Orange would good onstage during a daytime show, but under stage lighting, eh, maybe not so much.
I've heard other people talk about this (instrument colors and how things look onstage) before, so I think that there may be some validity to this theory.
Then again, I could be wrong.