The heart of jungle item abuse? Lol..? What other item has he used? Elder Lizard? He wasn't even the only one abusing it then. Evelynn was an ungodly abuser of that item while build Ability Power! And even then, it didn't get nerfed, it just got changed to Physical Damage causes it... This is literally the first jungle item Ezreal has been able to 'abuse'.
Only other item he got nerfed/changed was Phage, but that nerf was only to other ranged champions who were also using it, making them a bit overly powerful as well, so.... yeeaah.
I'm pretty sure Akali got Gunblade nerfed a lot harder back in the day than Ezreal has ever gotten any item nerfed now. Runeglaive is being nerfed in the next patch because Scarizard is a fricken moron. He's the one who seems to want this change to go through as he's mentioned on his Twitter when he brought up the Ezreal Nerfs not lasting on the PBE.
Honestly? They're gutting this item because of Diana as well. Laning Dianas have been taking smite in solo-que and destroying with it as well, but you won't hear any QQ about that because she wasn't the one brought into LCS. Laning Fizz is also pretty damn broken with this item since it gives him a lot more base damage in his combo for cheaper early on when his damage isn't so great. It's higher base damage was just better overall for laners since it completely removed the early game issue with a cheap item that gave a huge boost, just like a Trinity Force does for an AD Ez or Corki, except cheaper and used on Assassins.
When it comes down to it, Sheen just isn't meant to be in the jungle. It needs to be strong for junglers to be able to use it for clearing, but if it's strong enough for them, it's strong enough for a laner as well. Throw new item item into the game that increases magic damage to monsters and returns mana based on the damage dealt to monsters, make it combine with the jungle smite and turn into the old magus with boosted magic damage verse jungle monsters and mana return based on damage dealt to monsters.