Veigar's changes aren't all that bad
Now I understand that this is not going to be a popular idea right off the bat. People saw Veigar as one of the only very reliable ways to fight highly mobile champions because of his instant stun nuke combo. However it seems like everyone is focusing on event horizon's change rather than what they did with Veigar as a whole.
They gave his Q 200 extra range and it goes through the first thing it hits for a total of 2 targets. That's immensely powerful because it allows him to use it to poke and farm in a much safer manner than it was before. They want Veigar to be about snowballing that Q so that late game you're chuckin those bad boys all over town from safety. And if you land an event horizon, whether it's a stun or they're trapped in the circle, you can now attack them from safety with Q and W while they're in there helpless. If they're a highly mobile champion and try to escape, then they'll hit the wall and be stunned.
I understand that highly mobile champions are going to be a larger problem now for Veigar if they instantly show up and all in him, but in the long run, this is just a change of playstyle for the champion, not a direct buff or nerf. The skillcap will be raised, but he's still going to be strong. Hell, since his Q can in theory kill 2 targets in the same cast now, that means he'd get stronger faster, do better damage and be harder to beat.