It is the job of parents and the church to teach the Gospel and the heavier theological truths to children. Putting that responsibility on cartoon vegetables is not only unfair, but would probably be irreverent. Wholesome entertainment, with positive messages is great, but it is no substitute for work of the church.
That's the key point. Veggie Tales were, in my opinion, a fabulous supplement to other religious and moral guidance, one that I was happy to see my kids watching. Anyone who thought, "I've got a talking tomato and asparagus to take care of this so I don't have to mention Jesus in front of my kids or read the Bible with them," was making a silly mistake and should have known better.