Various reasons. Continuouation of an older design theme, laws and design regulations all play a vital part. Secondly is the cost of manufacture.
The model that my friend has affixed below IS the most sold model as it is sold in All of Asia, some parts of Europe and the US.
The G9 is a JDM. Japenese domestic model. The shape is slightly different but the car as a whole is the same. Everyone else enjoys VVT, we don't get it any locally produced version. The reason being cheap fuel.
So what the shape of a car looks like in part depends on where its destined.