Riot is making his kit less toxic by making it stronger when building AP than building tank. AP Ekko actually doesn't have problems in it, tank Ekko does.
Also, buffing him?? They're removing his passive slow, completely reworking his R heal, changing some things on his W, the whole thing is a MASSIVE nerf to the way that he's played currently, FULL TANK, and they have good reason for it: even AP Ekko, unless he's ahead, doesn't 1-shot squishies. Your Q, E, passive, and Thunderlord's typically won't be enough to burst someone down, but getting that speed buff will allow you to E in, throw your Q, autoattack, then use the passive speed buff to either run to make the Q hit them on the return or run away, throw down your W, and ult back when your ult reaches them.
Overall, the Ekko changes are a nerf to tank Ekko, which is what's toxic. His kit isn't toxic at all, the tank build is because he does so much damage and never dies. AP burst assassin Ekko has plenty of risk and reward in it and is plenty strong as is. If you're seeing people go 0/7 on him, it's because they don't know what they're doing. I play AP Ekko, and I'm pretty good at it. I haven't gone 0/7 on him in a while. Don't complain about his kit being toxic because tank Ekko, which the rework is designed specifically to put in the ground and cover it up with a concrete slab and 6 feet of dirt, is toxic, and don't complain that Ekko is bad because every Ekko player you've seen has no idea what they're doing with him. Ekko is a pretty high skill cap champion, but when played well, he's strong. The purpose of tank Ekko was to cover up his negatives without sacrificing damage, which it did a little too well.