Thaumatechnology - in a world where straight magic has an unnerving tendency to get the user killed, either by magical catastrophe or by being lynched by an upset mob, this is a much safer form of magical use… Even if it does occasionally explode.
As population increases, animal souls are promoted to human before they are spiritually advanced enough in terms of impulse control, etc.: this shouldn't have happened, but karmic progression is automatic, after all--it's a force of nature. But the 'animalization' of humankind bodes ill for civilization.
No doubt the same goes for elves, dwarves, and so on.