Here's why I think you are wrong on this:
You have to remember, that the folks on the macrumors.com forums are people who are REALLY in to the technology, and know a lot about it. WE may be aware of all of these fine distinctions, but 99% of the iPhone users out there DON'T, and have no clue about them. They just go to the app store and see something Apple has approved of and certified for sale, and think "That looks cool! I want to be able to do that!". Unlike us here they have no clue if there is any TOS issues.
If you then turn around and start terminating contracts, sending giant bills to the 99% who downloaded the program in good faith, it is a PR nightmare and possibly legally actionable against Apple(they are perfectly capable of blocking sale of the app in whatever countries they choose). They're just not going to do this without some sort of warning. The program will either somehow be disabled, or you'll get a stern warning from AT&T to knock it off or else(or 2.1, 2.2 firmware just disables it). Or they figure they got it off the App store early on, so only a handful of people have it and it is not worth their time to stop for a couple of thousand people. Just keep an eye out for people who are dling 10GB a month and go after them(whether they are doing it with NetShare or just the phone itself).