Great post, and I often think similarly. As Ross pointed out, though, there are many difficulties inherent in measuring the output of a workout. Another illustration compares overhead squats to back squats. In your analysis bodyweight squats move your entire body 2.5 feet. Your lower legs barely move, though, and your hips probably cover 2/3 the distance your head does.
Work and power calculations can probably show a lot when analyzing a single exercise and varying the weight, time and volume.
That's just my $.02.