Low screen/front-size ratio, big fonts to compensate low resolution, flat UI and "clever" menu layout to compensate low contrast. Consumer expectations are high these days...
For a $99 `feature phone' expectations are commensurately lower; I don't think anyone would buy this phone expecting something that's equivalent to an iPhone 5 or a Galaxy S4. They'll buy it because it's cheap, cute, does everything they want, and it has great battery-life.
You could say that, but Nokia had very similar designs (albeit with a couple more buttons at the bottom and a hidden keyboard) before iPhone. When iPhone4 came out I remember thinking how familiar some of the details looked.