Models are referred to as hatchbacks when the rear of the vehicle drops constantly from the roof to the end of the body after the rear row of seats.
Thus, a hatchback offers good space utilization and usually optimal aerodynamic properties. Vehicles of this form have relatively large tailgates to allow easy access to the interior. It is therefore no coincidence that this variant is the one that is most offered and also bought among all body offers, because it has proven to be very practical - regardless of the actual car size and class.
With the normal trunk it was also difficult to stow a dog, with the hatchback it can easily jump in and has more space to spread out.