On the rational side (in addition to aesthetics, preference, etc.). There's also aesthetics and probably a general feel that a sedan is a more serious adult car.)

Some people prefer a separate locked trunk.

In addition, small hatchbacks often tend to be designed as 2-seaters with a vestigal back seat as a way to maximize the use of the hatchback for cargo. As you get bigger you get something more like an Outback wagon or (increasingly) a crossover of some sort.