Why was Hunters Potion removed?

Because its useless and has no need anywhere.

"Hunter's Potion is an underpowered and seldom-picked option for players. We're removing it from the game as we don't feel it’s necessary in the current jungle"

Basically no reason at all. Honestly if this is criteria for removing an item then should have been removed as well.

It was a noob trap

It was only bought on non-meta junglers that needed a crutch for sustain. By removing the item riot has removed all trash junglers from jungling.