Exactly what I do, too. That's why I consider the "default ON" a bad decision.
I agree. The option should be there for them's that wants it. . . but off by default. I prefer it on, but I have a 15GB monthly plan for the family so it's not going to be a problem. Sometimes someone at Apple doesn't think the consequences of what seems like a good decision through. I think Steve Jobs would have vetoed the on-by-default option, though.