I think some of you are way overreacting to that picture. Apparently you never read comic books as a kid or watched any action or sci-fi movies. I can assure you I was exposed to the Paradise book, the Live Forever book, etc. and somehow I survived. Just saying...
On one hand, I agree. The illustration in and of itself isn't any worse (or as bad) as some comic books, sci-fi movies, etc.
But - kids know that comic books and sci-fi movies are make believe. It's not real, it's entertainment, escapism, even if they don't know the terms or words to describe it.
When you sit in a KH and study this material, or sit in your family study and have it beat into your head that if don't obey Jehovah, this is going to happen to you, then this isn't entertainment of a violent nature, it's, at best, indoctrination, or at worst, mental abuse. If these illustrations work on (simple minded) adults, then imagine how it can affect younger, undeveloped, immature minds.