I don't disagree with your response, but I disagree with what I understand to be your initial point: the primary reason that the F-15's interface is this particular way is because cost was not a barrier. While that is part of it, I don't think it's most of it. I pointed out operator training time, which is assumed to be huge.

But there's also a fundamental difference between a fighter pilot and someone driving a car. For a fighter pilot, everything they have to be able to do has to be at a hand's reach in a second. This is an operational requirement for both the "fighter" and "pilot" sides. Driving a car is different; there are many tasks that normal car drivers don't need to do while driving. It's okay for them to do them parked, after fiddling with a bunch of other stuff.

My point: it's not just cost which determines the difference, but training and task requirements.