I couldn't agree more with most of your points but I think that pass/fail isn't the right approach.
Taking an aggressive schedule in order to get your "I spent four years doing what I was told" paper and GTFO ASAP hurts your grades
Working a job hurts your grades
Extracurricular hurt your grades.
What I see is a simple duty cyle problem. Students have a finite productive capacity (not sleeping isn't a semester-term solution). If they take a schedule that requires more than a certain % duty cyle then they take a GPA hit. If you could account for the amount of productivity required by a class you can take duty cycle into account when calculating GPA. For example, 120 credits in 4yr is a lot easier than 120 credits in 3yr. Five 1xx or 2xx gen-eds in one semester is a ton easier than four 3xx or 4xx classes in a STEM discipline. Having some way to account for the extra effort required to run wide open for a semester or run close to wide open for 3yr would go a long way.
People playing the game (college) on easy mode (BA in business, no job, is a member of a frat with a really good test bank his major, etc) get the same GPA as people playing on hard mode (engineering degree with minor in something else, academic club involvement, works a job on the side, etc) and there's no way to tell them apart when it's all said and done.
If there was a way to score classes (and professors) based on typical grades then profs could grade how they want and students could take what they want and not be punished. You could do something like track the average grade for a class/prof combination and track average grades for students. You could eliminate the effect of one prof who teaches one of many sections of one required class as well as the effect of a bunch or really good/bad students enrolling in a class on one particular semester. You could also eliminate the effect of taking a ton of really hard classes or unknowingly enrolling in a section taught by a really tough prof.
Basically if you applied dynamic curves to classes at the university level then you can account for easy/hard classes, profs and schedules. There's got to be some catch but I can't think of one that couldn't be worked around with effort since it doesn't have to be perfect, just better than nothing. You don't need to make getting bad grades in four hard classes have an equivalent GPA to getting good grades in four easy classes, just making some way to partially account for the difference would help. Obviously this wouldn't be in the financial interest of colleges but that's a different issue.