It's a combination of a lot of things. Hurricane has always existed and even used to have more attack speed.
It's the availability of onhit items and how powerful they are. It's the fact he does hybrid damage and that's impossible to itemize against with %max health and current health also being a factor.
It's that he shreds anyone given a few seconds, and cc/peel typically lasts that amount of time.
Jungle Kog works due to a percent health on hit item with attack speed.
Wits end allows him to survive Mage bursts which are his greatest weakness. It also provides damage, attack speed, synergizes with rageblade, and makes you weaker to his hybrid magic damage while beefing him up.
Bork gives life steal, attack speed, on hit percent physical, some cute AD, and an active allowing him to kite.
Rageblade amplifies the rest of his kit and items.
Hurricane allows him to melt 3 targets instead of one. With all the onhit he builds, it works and works hard. Again, attack speed.
He has many items that just fit him perfectly, namely rageblade. It's an item balanced and built around taking time to ramp up with 8 autos (forgot if it's still 4 for melee). Even with a max attack speed adc, that's 3.2 seconds of build up. For Kog? That can be a simple 1.6 second build up. See how someone peeling or stunning a dive gives Kog enough time to fully build up and shred anyone?
Kog Maw is balanced around solo capabilities unfortunately when he's a champion picked for team play. Most champs are balanced this way. His weaknesses are no mobility, no defenses, no escapes, etc so the idea is just jump on him and he dies.
Now with a team of 4 others dedicated to protecting you, suddenly that weakness fades away.
With only 1.6 seconds late game to build up to full power, and a whole team ideally protecting you, it's no wonder you are one of the best hyper carries in the game. There is no champion (save maybe trynd), no build path that will remotely save you from Kog. He can and will shred any champ, any build, any objective in the game. His counterplay is to bring him down instantly or catch him out.
Overall, they wanted to bring hurricane back. It was an extremely niche item only used by the most extreme of onhit champs, being Kog, Teemo, and maybe Twitch. It gave pure attack speed, being valued as the aoe on hit item that just wasn't too useful.
Now it was revamped to give less pure attack speed but crit as well and keeping the aoe aspect. It brought the item back, but honestly not by much. It just made the item better for those champs already using it. Those that began using it post rework are champs that really shouldn't be having that aoe, like jinx and her rockets exploding in all 3 shots or Ashe and her multi slow. Kog was already using it as was twitch, so all it did was make them better and more fit for jungle.