"I'll peck, and I'll jab, at everything that makes you, you. We will scorch the earth under which he stands and the night will brighten with the ashes of the Federation."
That has "from hell's heart I stab at thee" written all over it.
Does it? One is a literary quote and the other is not (as far as I'm aware), which I'd think was a fundamental distinction. Nor are grandiose villain lines remotely unique to Khan. Hell, given that he steals a couple from Ahab and is obsessed with his target resulting in his own downfall, I suppose we should dismiss him as an Ahab ripoff from now on.
At least we've got Khan ripoff and 'memberberries out of the way - now we just need someone to be called a Mary Sue to complete the trifecta of the usual lazy kneejerk criticism.