Some of what you said makes sense and I've adjusted the list appropriately. Some of it is... the opposite of that.
Added:Innocent BloodWindgrace's Judgement
Not added:Valorous Stance: If it said 4 or less it would go on. But 4 or greater is too narrow a target.
Ravenous Chupacabra: 4 mana sorcery speed is not good for only one target. Even 3 mana sorcery is questionable.
Maestrom Pulse: oh look, 3 mana sorcery speed. While it can hit any target, there are other options in this color pair that do that. Better options. At instant-speed.
Duplicant: It makes absolutely no sense to me why this has to be on the list. 6 mana sorcery-speed is really bad. Incredibly bad. To top it off, it only hits creatures, and doesn't have built-in multiple uses (like the planeswalkers on this list). Why on Earth do you think it should go on the list?
Removed:Banishing LightOblivion RingChained to the RocksDeclaration in stoneOblationWinds of AbandonAttritionMurderLightning BoltMizzium MortarsNot removed:Chain of Vapor: it is still creature removal, and the best option in blue.
Expel from Orazca: see previous comment.
Cast down: While not able to kill legendaries, it still has a wide range of targets. And it's a 2 mana instant.
Doom Blade,
Go for the Throat,
Malicious Affliction,
Price of Fame, and
Victim of Night are all amazing pieces of creature removal. They are all 2 mana or less, and instant-speed, with a small limitation of targets.
Snuff Out and
Vendetta require special attention. These are arguably the two best creature removal cards in black, because they cost 1 mana and 0 mana. There is nothing wrong with them.
Merciless Executioner and
Fleshbag Marauder: While strictly worse than
Plaguecrafter, they are still good, and used as redundancy pieces in the same decks.
Sudden Death,
Sudden Shock: Split Second is a combo stopper. If you don't go up against combos I can see why you might think they're bad.
Abrade: It has the duality to get rid of creatures and artifacts, at instant speed, for two mana. There is nothing mediocre about this card.
Fall of the Hammer,
Outnumber: I've already give the disclaimer for these cards.
Final Payment,
Mortify: I don't see the problem with these cards.