I believe that in order to understand behavior, which we have determined is the nervous system, we have to start at the most basic element of the NS and understand how it works. In other words, yes, it is worth spending a week (and even more) on learning about potentials. Once we discover how neurons relay their signals, we can observe how an individual is affected by these signals, and what kind of signals (or which) are produced by certain behavior. These observations may provide information that could enable us to explain simple behavior in terms of potentials; the explanations of the simple could help us understand complex behavior in the same terms (potentials).
I think you're right, but its interesting to try and understand exactly WHY this is so. After all, one could use the same (basic element) argument to say that we really ought to be starting with carbon, hydrogen, and oxygen. How does one guess where to start? And how decide whether one has started at the right (or at least a useful) place? PG