Why the Veiger changes were good
*****disclaimer: I have not played the new Veiger yet, I have only played with our teams mid laner while he was playing him over the past 2 days. Take what I have to say as a purely speculative opinion.
With the new Veiger changes, I feel as though they are giving him the Ahri treatment, and by that I mean taking his role as a Mage-Assassin to more of a Mage-y Mage. And I know you guys are going to say "well wtf veiger still 100-0 people," and I know he can, but now with his stun having a cast-time-animation-delay-thing, he doesn't (or shouldn't) be playing like he was pre-5.4. Its too unreliable that you are going to hit your stun that you would play super aggro and in harms way to get a pick or something.
I like his new Q, giving him a more Mage-y feel to him. Kind of like, well just like Lux bind, except not binding. It gives him more damage, and especially more scaling potential, being able to hit more creeps with it if done correctly.
His ult ratio was reduced to compensate for all this extra AP, but I do think that it is still as good, if not better, than his old ultimate damage. This is because stacking his Q is a lot more effective if you prep the wave correctly and do it correctly and get 2 creeps per Q as much as possible.
tl;dnr more damage, less safety tl;dnr playstyle change