Mass produced basses are bound to have that, as black goes with everything and it would knock prices up to do something different.
Luthier-built basses are a bit different in that they're not coming off a production line. However, how do you do the pickup? Commercially available soapbars are black rectangles, which have been encapsulated in resin. Options: put them in the bass as they are, put them inside little wooden coffins and put those in the bass, make your own pickups. Mostly it's the first option, Jaydee I think went with the second, not sure about the third - Enfield perhaps? Going with the first option means you're routing out standard sized holes, and somewhere down the line if someone wants to change pickups, they can. Not sure if putting a veneer cover on a pickup would look OK - maybe I'll try some <Blue Peter> sticky back plastic</BP> on one of mine.