The key part of that article:
"AT&T charges $25 for 2 gigabytes of mobile data, which states how much they think their bits and bytes are worth. That comes out to 80 megabytes per dollar. 80 megabytes will get you 500,000 text messages—assuming you're writing the largest possible message, which you're often not (i.e. "Hey" "Nothing" "lol").
Now divide that dollar by the 500,000 potential texts. That comes out to $0.000002 per text—two ten thousandths of a cent. A very, very, very small amount of money.
Now, let's say you send 5,000 texts a month. That's a large, though wholly realistic number. Multiply that by the above worthless cost per text, and you've got—hold onto your wallet!—$0.01. A penny for five thousand texts, according to how much AT&T says its data is worth in a data plan.
But outside of the data plan? Oh boy! Things get very different very fast. And by very different, I mean inordinately overpriced. Those same 5,000 texts, at a rate of $0.20 per message, will cost you $1,000. Not a penny—a grand. Two very different prices for literally the exact same thing."
Read the rest of the article for the painful details - especially if you are on AT&T. Of course (again, as Gizmodo states), the rest of the carriers will likely follow suit in the near future.
Because, you know, it's all about the customers. And by "customers" I mean "stockholders", not "people who buy our stuff".