Apparently many cultures throughout history practiced artificial cranial deformation.
But… Why make your kin look like extraterrestrials from a B movie?
It looks like the usual suspects for dumb herd behavior are in play:
One modern theory is cranial deformation was likely performed to signify group affiliation, or to demonstrate social status. Such motivations may have played a key role in Maya society, aimed at creating a skull shape that is aesthetically more pleasing or associated with desirable attributes. For example, in the -speaking area of Tomman Island and the south south-western Malakulan (Australasia), a person with an elongated head is thought to be more intelligent, of higher status, and closer to the world of the spirits
This of course prompts the question: what is the equivalent of cranial deformation in modern cultures? What things will future people consider similarly… shall we say… misguided?