Riot has trouble with Kog because they're pulling him in two directions
They want Kog to function as the primary (or only) damage source for his team. This means he needs a godly mid game and a solid late game so that he kicks in when team fights are starting to pick up. If his team-fight phase isn't amazing, then why not pick someone more self-sufficient? For this role to work, Kog needs powerful base damage that doesn't scale appreciably so that his mid-game is potent without making his late game absurd.
They also want Kog to function as a late-game hyper carry. Kog briefly filled this role when his remade W got an AD ratio, but Riot quickly crushed it. A hyper-carry is, for the most part, going to work best as a self-sufficient champion. They function as a sort of backup plan for their team since their damage doesn't really kick in until late. For this role to work, Kog needs either a heavy AD ratio or critical strike interaction on his W so that he scales powerfully with items into the late game.
If you try to make Kog do both of these things, then you end up with an abomination with crazy-strong Mid AND Late game that quickly gets out of control and eats the enemy team. So... basically what happened with the machine gun Kog remake. If Riot wants Kog to work, they're going to have to decide whether they want him to be a hyper-carry or a mid-game carry and stick to it, otherwise they'll just break Kog again.
