Exactly. This may sound crazy, but I'm actually considering dumping my unlimited data for the 3G plan. Why get throttled at 2GB when for the same price I can get 3GB?
Because eventually with how fast mobile technology is moving, you're going to be using a lot more than 3GB.
Just because you don't use that much now doesn't mean you won't in the future when everything is digital. Data consumption has increased almost exponentially in just the last year, imagine what it's going to look like in another year when there's a 4G iPhone, but you can't use it as much as you want because you will go over your data plan.
They WANT people to get rid of their unlimited plan for the 3GB plan for the same price because eventually they can charge even more when 3GB isn't very much. That's why they introduced a 5GB plan. Data usage is increasing and they want people to pay more for an allotted amount than pay less for an unlimited amount.