Where's my violin?
Every carrier provides tools to monitor your usage, and third party apps exist to do the same. You have no one to blame but yourself if you incur an overage. Additionally, Verizon (can't speak for the rest) allows you to backdate plan increases. They've done this as long as I can remember. If you're even slightly proactive about it you'll never pay that $15/GB overage. I've had service with Verizon for almost a decade now and I've yet to pay any sort of overage.
seemingly oblivious to the possible impact $15 per gigabyte overages could have on the heavier users
As usage patterns change the caps will change. As the market matures the carriers will be forced to compete on price, right now they don't have to because it's a growth market with new customers flocking in by the droves.
The sky is not falling, despite all claims to the contrary.