These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Accidental Innuendo: Konquest Mode involves collectible "Relics" for each character in the game. Moloch's is the ball and chain he carries around...but it's called "Moloch's Ball." Cue Heh Heh, You Said X.
Crazy Awesome: Havik, continuing one from his Deception debut. This line from his doppelganger sells it:
Havik: "Looking for trouble, I hope?"
Game Breaker: Sareena is seen as a high-tier character for one reason and one reason alone: her knives. As Ed Boon best put it, they are among the fastest projectiles in the game. You can also juggle opponents with them, leading a few combos rivaling Kitana's infamous fan lift setup in terms of litigiousness.
The air combo system has a fatal flaw: If you drop the 4th hit in a combo after making them spin in mid-air, you can leap right back up and do it again, resetting the combo and trapping them in an infinite loop unless they have a Combo Breaker.
Harsher in Hindsight: Shao Kahn's position in the poster featuring the cast of the game, showing him directly under Blaze, dead center in the top row. Now, consider who won the final battle.
The developers themselves were disappointed with Shinnok in Mortal Kombat 4 and were satisfied with his moves from Armageddon.
To a lesser extent, Jarek, basically has new moves in order to stop being called as the Kano-Klone. Altough he's more of a Base Breaker than fully rescued.
The Scrappy: Two-legged Motaro, considering it removed one of his most noticable traits.
Daegon. He's considered a bland and boring villain who formed the Red Dragon just to kill his brother Taven.
Taven also gets a lot of flack from the fanbase. Also a Replacement Scrappy for the already disliked Shujinko.
Scrappy Mechanic: Create-A-Fatalities, one of the most critically-panned aspects of this game, since it blatantly took the place of the game's classic Fatality system and replaced it with generic cut-and-paste finishing moves that any character can do.
That One Boss: The Shao Kahn Colossus statue in Konquest mode. He's completely invulnerable to your attacks, you can only cause damage to him by activating four orbs with your fire attack, and then lure the statue to the center of the room before hitting a switch with your Ground Stomp attack. Oh, and you can't avoid his attacks. No matter where you are in the room, you will always take damage.
Vanilla Protagonist: Taven. We're supposed to focus on the titular battle royale between the entire cast. Yet the Konquest Mode is about him trying to stop said battle.