This post previously appeared on Business Insider. By Steve Kovach A new report is out today that says Apple is testing larger screen sizes for upcoming iPhone and iPad products. Apple tests stuff all the time, so don’t take the report to mean that a big-screen iPhone launch is imminent. But the question remains: Why has Apple dug its heels in the ground when it comes to making phones with larger screens, especially when rivals like Samsung are selling tens of millions of them? Here are the reasons according to Tim Cook, which have been rehashed many times over the last several months: The iPhone is designed for one-handed use. The iPhone 5 has a 4-inch display, which is still small enough for most people to use in one hand. Making a larger iPhone would reduce image quality on the screen. Cook has said making a bigger iPhone screen would mean tradeoffs in color and resolution. (However, Apple makes a 9.7-inch “Retina” iPad with an amazing screen, so this argument is a bit odd.) It would be tough on app developers. If Apple makes a bigger iPhone, developers will have to change their apps to fit the new screen. In the meantime, apps would have to run with a black border around them. That’d be a pain for developers and a less-than-ideal experience for users. Of course, Apple is notorious for saying “We won’t make X” and then releasing such a product a few years later, so take Cook’s statements with a grain of salt. The iPhone, iPad, video iPod, and the iPad Mini are just a few examples of products Apple originally said it wasn’t interested in making.