I'm a top tier veigar player... and boy let me tell you why you're completely wrong!
As is, if you didn't hit your cage perfectly, if the enemy had .2s before they walked into it, they'd dodge it. The most you'd be able to do is trap someone inside of it now. Anything above silver and you might stun them 1/10 times, if you're lucky.
As far as my level of play goes, if they aren't stunned, even if they are trapped in cage, you're not hitting W. It's just not going to happen. If I miss my stun I don't bother W'ing as it's just not going to hit. It's now a spell solely for farming minions.
Now onto his Q. For a very good reason, the majority of veigar players think you're supposed to farm your Q. You're not, if you have time to farm your Q, you're wasting mana, Wasting time to harass, or Wasting time to roam. Basically you shouldn't actively use your Q for the reason of farming. I cast it on minions for last hits just for convenience and not for the AP it gives. Every veigar I see who actively farms their Q I laugh at because they waste mana and give me a free lane and they're not going to be having consistent games, basically rolling the dice on whether they're going to win. Another reason why it's a bad idea to farm his Q is because he's a mid game champion who was completely reliant on the bonus ap. The most bonus ap from minions you can get in 7 minutes is 34, just 34. That's if there's no one else in lane. 34 is not worth wasting veigars strongest points in the game which are early/midgame.
The reason his late game is bad is because everyone gets a banshees and makes his E un hittable, but now his E is unhittable anyways so it doesn't matter. His whole game is going to be poor now.
With an average base movement speed, you can travel ~300 units in .75s. They increased E's range by 50 units, so they also nerfed it in it's chasing and catching aspect, so only if they're close enough to be already killing you you won't be hitting your E. Veigars strongest attribute was his Catching, which is Gone.
If I took the current veigar into a ranked game in diamond, where I could previously get 0 deaths and 10+ kills and secure the game by 10 minutes, I'd be unable to hit my E 95% of the time, I'd NEver hit my W except maybe in team fights, and my Q can now be dodged and is fairly unreliable. The ult is useless now so I'm not even going to mention that because that was just a nerf to kick an already dead dog.
Veigar is gutted. Everyone who has the slightest real experience with veigar also agrees, and every opinion above plat has been that veigar is pretty much useless.