If I had to guess it's because they're $0 phones and often come bundled with inexpensive unlimited texting plans.
If you're a thirteen year old girl that sends a hundred texts a day, which is actually the average, then a you'll want the one with the physical keyboard.
Plus, the Blackberry Pearl doesn't look that bad as far as phone gadgets go. You can even pick from a variety of colors, something which the Android and iPhone offerings lack without spending extra on a case or stickers.
