These "averages" are incredibly deceiving.
Many smartphone users don't even think twice about streaming music for extended periods of time, esp. if they have a dock, or use it in their car. Add in occasional video, regular checks of websites, misc. navigation, misc. app downloads, etc., and you easily hit 2GB/mo. Sprint users who have 'unlimited' seem like they like to use their data without fear of any extraneous charges, which is good.
Usage is only bound to increase over time, especially with 4G.
These data constrictions are in place for two reasons - money, and scaring people into using what they pay for in a lesser manner.
According to the "network monitor" app on my Android, I've used over 400MB this week, 1.4GB this month (so far).
agree with the not thinking twice about streaming music. i just checked my usages on Verizon's website. half way through the billing cycle i'm at 900MB, my wife is at 400MB, and my daughter is at 1.6GB! i was surprised at her usage being so high, but she does stream music non stop and browse the web at the same time.