I think I've said my piece on why Ken is an awful character in P3 & Marie Golden, so I'll just provide some counter thoughts to Astus post here.
This is essentially it. They've flanderised the character and the voice acting has been moulded to fit. I have no doubt that Wittenberg would have drawn the same criticism given the script and direction for Teddie in Q and other assorted spinoffs.
Despite all that though, I don't think it's quite as bad as the JP VA. That's just on a whole nother level.
While there's truth to this, however, voice acting is in large due to performance of the actor and quality of the voice direction. Excellent voice direction can make wonders, see The Last of Us documentary for frame of reference - There you have Troy Baker, talking about how long it took before he finally found the right tone for Joel, without his tendency to resort to his awful melodramatic overacting ala James Sunderland in the Silent Hill Collection.
Heck, Wittenberg might not have been able to save Teddie from the awful caraciture-framing of Q but he's at least still sound like Teddie, I'd wager.