Agreed. I really don't know what riot was thinking.
But you can assume, based on what they r writing, they they did not think much and they don't know much about the champion the trying to change.
Some of their quotes about Veigar (mostly something what Bronze player would say about Veigar):
"When we took a step back and thought about what the ability was really trying to get at, we saw the ideal Event Horizon being more about trapping your opponent in a cage for Veigar to torment than simply about stunning a dude at 1025 range."
"By amping up the AP farming mini-game on his Q, we're creating a new path for Veigar players to achieve their dream of pressing a single button and watching an enemy disappear."
"While 0.2 is a sizeable hit to his Ult's ratio, I want to stress that Veigar is getting quite a bit more AP from his Q in this version than on live" - such bs, it's actually harder to farm with new q because it's generally less reliable, therefore players in all divisions will gain less last hits from that than before or same amount in best case scenerio
"While we recognized and intended to preserve Veigar's role as a 100-to-0 burst mage" What? By reducing power of all his abilities by 20% and then decreasing ratio on his ult from 1.2 to 1.0 AND making sure his meteor never hits target?
The best one:
"Veigar traps his prey in a chamber of horrors and shoots Baleful Strikes at them and drops Dark Matters where they have limited space to dodge."
Pretty much sums up Riot knowledge about Veigar and how this champion was even played despite of fact that most other mid laners did their jobs better and were more reliable (which is why we didn't see mid lane Veigar in tournaments).