I can think of a couple of reasons why the Navy doesn't include flight controls for the WO/Navigator. One is to avoid two opposing inputs in combat, with the non-rated type intervening when they shouldn't. The other is rooted in cubical critter stuff: the WO/N would have to also be carrier qualified. It's hard enough to get/keep pilots qualified. Plus, the "other guy/gal" typically doesn't meet the vision requirements for pilots.
A reasonable person would figure that if the "other guy" can get the aircraft back to the carrier, you combat loss the plane and the crew ejects. That's typically more creative thinking than you'll find at high levels. Especially since with one set of controls, if the pilot buys it, the plane is a loss anyway.
Added edit: IIRC, the AF version of the F4 gave the backseater rudimentary flight controls to allow getting the plane back over friendly territory.
It's been decades since "tactical" became code for black, nylon/plastic, 3 times the price. I guess now, you could add field dark earth to black.