I think that the answer to this maybe a range of factors. Along with improved technologies like power boxes there has been a general increase in consciousness of our systems requirements, and in particular the air borne battery/power systems. Reasons;

1) In the last few years all models, not just jets, have tendered to be come bigger and more expensive. (people are prepared to invest more in preventing a crash).
2) The shift to 2.4 has made it absolutely critical the RX voltage remains above 3.5 volts.
3) The advance in battery technologies and more particular chargers, give us much better tools to charge and monitor our batteries.We have moved on from using a simple wall charger to trickle charge our 1000 mah Ni cads, and hoping for the best.

I know there was a big turning point for me when I moved to JR/Spretrum 2.4 a couple of years ago. I educated myself on the brown out issue (which simply requires a robust power supply to avoid) so I did a bit of basic research. I now know things like how much power my model uses in a typical flight, what each of the servos can draw when stalled, and how much capacity is available in my battery. Most of the guys here that fly jets know this stuff. I don’t think this was the case a few years back.

Power boxes are just one of the gizmos that have become available in the last decade. They are undoubtable useful in some applications, maybe not in others, but they are a part of the ongoing development of safer systems in our toys, along with a real increase in awearness on how to build a safe system.

Roger