I don't buy the premise that there was a time when paint jobs were generally more elaborate. There are always standouts, but generally bikes are single color with brand graphics.
I might even argue that bikes are more graphical now than they've ever been, because it can be hard to find a plain, solid color design now.
Take a look at Trek, for example. In '00, you could get a red road bike with white brand/model designations. By '05, they were full into the curvy, multicolor accents. By '10, the panel painting thing started, where they'd create a line on a portion of a tube to mark a contrasting color block on the underside, for example. It's basically the same thing they're doing still, doing lots of graphic detail work to give visual interest rather than just painting the frame a solid color.
So yeah, I get that matte black is en vogue, but I don't agree there is less graphic design than before, and in fact think there is more. It may be there are fewer color options for any given model, though, and even that paint trends are towards matte finishes and abrupt transitions, and less of the glossy fades, but again, that's different from saying there's less graphic design.