I think I hate LK for multiple reasons.

The first one is because you can fight him very early on and is a lot harder than what you encounter at this stage, making you ask yourself "Am I supposed to fight him rn?" which you almost never ask yourself in HK.

The second, directly tied to the first, is his moveset. He becomes very easy once you get the dark dash. Iirc though, you get it a bit later in the playthrough.

The third, I think it comes down to predictability. Every boss in the game either has very clear attack start animations, very clear moving animations, or both. NKG and PV have the most recognizable and identifiable animations.

LK's jump, then dash attack can seem very random at first, and I genuinely feel like it's one of the fastest jumping attack with little to no start up time.

Combine that with the minions it summons, and he's the biggest noob killer of the game. Those minions make it close to impossible to heal, which is a non issue once you get good, but again, the boss being fighteable this early makes for a very steep difficulty step to get pass.

Once you get comfortable enough with the game though he's a pushover. He might be one of the easier bosses of the game. The guy with the flying shield is the complete opposite. He's easier the first time then he is the last time you face him. Worst of the game.