Malbim (Derech ha'Muskal): Hashem put in their nature to band together and not separate from each other, even though this harms them. Via this, it is easy to eradicate them. Hashem gave this nature so people will learn a matter of Chachmah. All powers of the Nefesh should unite in one bind, via conducting according to the laws of Chachmah. This is the opposite of a hated woman who has Bi'ah (23) - powers opposite to the laws of Chachmah are scattered and oppose each other.