Animals have parasites and diseases, so do plants, there are even bacteria that cann dissolve oil spills or plastic or what have you - why couldn't there be a disease living off magic - a magic item could be infected, losing power and speading the plague to other equipment it contacts, while a magic user would slowly lose his powers and contaminate all he works with or casts a spell at...
In this culture it is not wise to talk too much good things about anything - especially children,lest some evil spirit steals it. So it is customary to say it is ugly and weak and will surely not survive. Also:
"The man who boasts of his young woman is a fool,
The man who boasts of his wares will get rich."