First I want to give Kudos to Jon Schindhette. One after another he tackles really tough topics in a way I personally can only applaud. He strikes me as very professional and this blog makes me wonder why we didn't read more from him before, considering how long he seems to be involved with D&D.
So, I've voted full gore and violence for this one.
While I don't want it to be everywhere, I got my reasoning from my own first autonomous steps in gaming. You see, at the tender age of nine, I got the 2nd edition box of the Warhammer 40k and thus access to that games art, which fully falls in line with that option.
I mean:
Disfigurement- check
Mortal wounds- check
Landscapes of demonic terror- check
Beastmen and Chamions of Chaos, holding up severed heads and drinking the blood pouring forth- check
Now, I don't think every nine year old should be exposed to this stuff. But it reminds me that art of that level is not necessarily a hindrance to non-adults entering the a gaming hobby.
The art of the warhammer games is to this day some of the most evocative in all gaming to me. It relly gets the point across that it's villains are real beings of darkness and madness (and that everyone else isn't much better).
While D&D isn't as dark (and by default shouldn't be), it has the whole gallery of devils, demons and other nasties. And I want those creatures depicted as the evil they are. Demogorgon should visibly be a whole other level of threat than the humble (and adorable) owlbear, even though both are strange mix and mesh monsters.
So yeah, while I don't think D&D books should be drenched in depictions of gore, the art should be open in all directions.