I see no reason to lower the bar for the lowest common denominator. There is a reason that engineers with a 3.0 usually still have no real problems finding jobs, and that’s because even when they don’t understand the ins and outs of the N-S equations they still learn useful skills. The ones who excel in those sorts of topics get the “top” jobs that you are alluding to, and the ones who don’t have plenty of jobs to choose from that don’t require that. On top of that, hopefully by at least being exposed to the material, even if they didn’t fully grasp it, they will know where to look in the future if they do have need of it later.
In this sense, you are correct that the market has already drawn the line. Those jobs like airplane CFD guys are hiring up the students who excelled a little bit more at things like the N-S equations, and the jobs that will never require that again are perfectly content taking those guys with a 3.2 GPA that really only picked up the practical skills and didn’t really excel at the theory.
And yes, I would love it if every student exhibited true technical fluency. That’s the Utopian goal, in a sense. Sure, I am pragmatic enough to know it will never happen, but that doesn’t mean we shouldn’t strive to get as close to that as possible.
For students who have zero interest in that stuff, they can always go get an engineering technology degree, which is a course of study that I think is probably underutilized in modern US curricula and industry.