I really enjoy this idea. I always loved looking at a monster log and reading about the enemy. Puts things into perspective and makes the game itself much mroe in debt and real.
As long as certain key monsters are already in my beastiary such as Glint, the Lich, and Shiro and what not because I've gotten the bonus in Dragon Lair and Capped X boss I should already have all of them unlocked.
Man, with all these new Nightfall monsters I'm seeing I want this to happen more and more. For some reason, I'd like to get a good look at the Skree harpies. You know... when they're not screaming at me and hitting me over the head.