How many devices on those list are 7+ inch? That's the point. There are few devices that are marginally higher DPI than few years old iPhone screen. But we are still speaking about mobile phones, not tablets. Reading PDFs on high-dpi 4 inch phone doesn't really improve anything, it's meaningless. 10 inch screen with similar DPI as iPad 3 is very fine for reading usual documentation. So, we're still waiting for decent competition in this area.