This is an absolutely insane take. Vicious Mockery is the the least damaging cantrip (or like bottom three). Further, it's a cantrip, something players are supposed to be able to easily without resource consumption. Expecting a player to come up with unique insults every time they cast this is stupid and exhausting. Also, the reason it's "as effective as power word kill on common folk" is because common folk are weak and meant to weak. They're not heroes.

Spell casters using cantrips is akin to fighters making normal attacks, swinging a sword.