I average about 15MB a month usage* and pay for the $15 a month plan. The fact that it comes with 200MB is useless to me. If I wasn't being grandfathered in, I'd be paying $20 for the same 15MB. That's why this price hike is just that and not something in service to customers' needs. People on the bottom plan want the cheapest plan, not 200MB or 300MB or whatever. They want the cheapest, and whatever MB that comes with, they will stay under it.
*I'm on wifi at home and work and already have dashboard GPS/nav built-in to my car. And I disable push notifications for everything except SMS and Phone calls.
That's my personal usage though. I have 4 lines on my account, 3 of them iPhones ($15+$15+$25). I'd like to upgrade the 4th to an iPhone, but now that's absolutely never going to happen because it will cost another $20 instead of $15 (and it won't need 200MB, much less 300MB).
I want a family data plan. Something like $50 total to allow 4 iPhones to share even 2GB data would lower my bill while allowing me to upgrade that last line to an iPhone and not even impact anyone's data needs. But I suspect this will never happen because those per-phone data plans are how they do the math on recouping their smartphone subsidies. Maybe it's time the subsidies end in favor of drastically lower data plan costs.