why thresh gets compensated for landing an hook against minions or monsters?

so does morg

WHy shouldn't he?

Compensated? how so?

I believe the issue he is referring to is the 3 seconds that are taken off the cooldown if you land the hook on a target. I'm pretty sure this was put in for punishing players that miss the hook as the cooldown of the hook is quite long (~20 seconds at rank 1). The 3 seconds off the cooldown is a small difference at earlier ranks. This "compensation" you speak of is not really compensation as the mana costs are still the same if you land the hook or not and the cooldown is not completely refunded.

Because Threshs hook isn't anything like BLitz'?

He only drags things closer to him or pulls himself to someone, whereas Blitzcrank can only pull them directly on top of himself

IIRC, they increased the cooldown and gave compensation for landed hooks as a nerf. This meant that people who landed their hooks had the cooldown unchanged while those who missed the hook received a longer cooldown than before.