I think it boils down to AT&T's inability to provide data service for the millions upon millions of additional customers the iPhone has brought to the company. I believe they are having a hard enough time keeping the ability to call out reliable let alone providing services that allow for a lot of data flow back to the their servers / network. I am no expert but it is the only logical reason I can think of. The amount of customers that the lack of these features deters is considerable. I am sure AT&T wants as many customers as they can get so to disable these feature from such a wonderful device can only mean they can not handle it at this point. The lack of the tether feature is something I am really... really disappointed in...
Sorry about the "on" in the title... trying to type this and take care of my infant son at the same time... lol
Sorry about the "on" in the title... trying to type this and take care of my infant son at the same time... lol