Well, there's a good reason for that prevalence. Used properly, even a basic VFR moving-map GPS offers far superior situational awareness and performance information (ground speed, winds aloft, etc.) at a fraction of the pilot's time and mental effort. There's no longer a need to waste your time by futzing with a stopwatch and an E6B trying to figure course correction angle and groundspeed; now you read them off, sanity check them, and get on with actually flying the airplane instead of playing human calculator. Anecdotal evidence from multiple sources attributes a significant reduction in CFIT accidents to the widespread adoption of GPS. I'd also guess that there are probably fewer lost airplanes and fewer airspace incursions.
Now, there are valid concerns about GPS dependency, especially related to user competency and failure conditions. That is, what do we do about pilots who don't know how to work the device, and what do pilots do when the GPS decides not to work? The response to these questions from a large part of the pilot population (and the CFI/CFII subset) has been to avoid the topic altogether--to pretend that GPS doesn't exist, to ignore it during training, to continue teaching navigation with the same methods used 25 years ago as if they were the only way to ever navigate. I think the unstated belief is that, once the student is done with training, he or she will continue to fly that way forever, and never be vulnerable to GPS failures because they'll either never use one, or will only be using it as a backup to their trusty E6B and stopwatch.
Unfortunately, that's not how things actually work out. What's much more likely is that the new pilot finishes training, gets hold of a GPS, and realizes how much easier and simpler it is to use. They immediately start using it for all VFR navigation, the now-expired paper sectional gets tucked away in the bottom of the flight bag to cushion the GPS or the headset, and the E6B slowly corrodes in a drawer. Now, I know some of you are thinking at this point "well, what happens if the GPS fails, huh? What then?"
This is why I believe that flight training needs to start catching up and coming to grips with the fact that GPS is now almost universal in light aviation. Instead of pretending that GPS doesn't exist and trying to dissuade pilots from using it, flight training ought to be teaching pilots how to use GPS appropriately. That means ensuring that the pilots are proficient with the system (know how to use it, what it can do, and what it will do after any given input), teaching pilots to use and monitor it responsibly (cross-check what it shows with what you see out the window, see whether the numbers make sense, fly the airplane first before fiddling with the GPS, know which direction and how far to a diversion airport, etc.), and teaching them what to do when the GPS fails.
This doesn't mean dropping traditional navigation entirely; it can (and should) be taught to some degree. But I think the hours I spent during my training trying to beat the E6B into submission and measuring lines on a sectional could have been put to far better use. Personally, I'd like to see less emphasis on enroute hand calculations paper navigation and more emphasis on AOA awareness and aeronautical decision-making, because those are the things getting people killed, not forgetting how to use a paper chart.
