I can imagine budget constraints making professional voice actors too expensive. I can even imagine being so broke that even paying some local theater group ten bucks a piece to do the job is too much. So I can understand having your animators and programmers do all the voices. But would it really cost that much more to do a practice read first?
Imagine you're a child and it's Christmas. A well-meaning grandparent has bought this for you. You gasp with joy- you've never heard of this part of the Lion King franchise before!
Then you start to play it. You're only a kid, so you can't really articulate what you're feeling, so you just cry. Until the day of your death, that day will be burned into your memory at That Shitty, Shitty Christmas When You Learned About Grey Areas In International Copyright Law.