While I understand where you are coming from, I can't say I agree. On my end, this is an improvement, because now I can make a Rylais/Frozen Mallet and I don't have to think about building some AD, but it's still a nerf to his endgame. Which, mind, wasn't even the strongest one on the game. RIOT keeps talking about the "hypercarry fantasy" but critsticks like Trist/Jinx and lately MF STILL have better scalings late, due to their attacks being far stronger (because the abbundance of crit chance items), their mobility being better (they all even have better MS, in addition to ways to boost it), and their range being almost as good (Trist passive, MF's reach is actually rather imposing with Q and R and Jinx's has her range be bigger than Trist's), and they all have steroids with little tradeoff (MF and Trist raw AS boosts, Jinx the snowball from her passive now). Certainly, he kills tanks better, but it's simply hte "DPS vs Burst" dillema and how burst ends up winning in LoL all the time, unless absurdly broken (case in point: the amount of changes that Ryze has had over the years were all based around him being a "machinegun of spells" and he is never i na good place because he eather deals no dmaage and gets ruined by burst mages, or deals too much and ruins everyone else). Same with Kog. he can't build AD and Crit, so his attacks are painfully weak and WEAKER with his W. Of course, the % of max HP on every attack is good, but it usually isn't as good as a 3rd of your HP from ONE attack lategame (and he can't ahve that, for obvious reasons).
Adding that 2% is nice, but it's completely off the mark IMO, and it's ESPECIALLY not worth nerfing his lategame for the sake of well, just not helping his early game much eather...