While I agree that building some kind of data compression into iPhone (perhaps like that built into Opera?) would have been helpful there are certainly additional costs and tradeoffs involved in providing for that.

HTC, Palm, Samsung, Motorola et al do not support a back end infrastructure to compress data for the carriers. Why should Apple be criticized for following their lead here?

The only device makers that do provide such an infrastructure are RIM and Danger. And arguably saving bandwith was an after thought when implementing those systems, it was more about security and convenience in my opinion.

AT&T failed to plan ahead and failed to invest enough into their network. Now they are victims of "their" own success. (I say "their" because iPhone is selling in spite of AT&T, not because of them. Apple is doing most the work when it comes to marketing)