Black and white are ancillary colors to the scarlet but they are not classified as official colors. You can find mentions of "scarlet and white" and "scarlet and black" almost from the start of scarlet being voted on by the Rutgers students in Kirkpatrick Chapel on May 17, 1869.
There have been times when the scarlet and other colors were used. The 1938 team wore scarlet jerseys and gold gabardine pants (because the manufacturer of football pants made them in that color). In 1915, Rutgers wore maroon colored jerseys because the dyes needed to make them scarlet were scarce because they came from Europe during WWI.
But usually the different colors were due to circumstances beyond their control. That is certainly not the case today.
My own opinion is that with all the new "looks" and colors, you create a generic looking football team with generic wear. That goes for us AND our opponents these days. We wear black, the opponents wear black. Everyone has their "black look" and the result is that everyone basically looks like all the other teams. What was once a special look is now the flavor of the week. Nike, or whoever is providing the uniforms, then markets the knock offs and makes a bundle. So they're just interested in anything different they can change on a school's uniform so they can sell that year's "model." They couldn't care less about a "look" that represents your school over the long haul. At this point, you barely see the school's acknowledged color on some of these uniform selections.
Next up on the "how do we make a buck off of college football teams" ... well why don't they just put corporate logo patches all over the uniforms like they do for race cars. And do we really need "R" on your jerseys? Maybe the producers of the next Superman movie will pay us to put an "S" on there instead.
And do you really need to call yourself Rutgers? Let's sell that off for a 10-year naming rights contract. I'd suggest we do the same for the Stadium too but someone beat me to the punch.