A Look at Monster Book

So... why is this so good?

I mean, I understand that the drop list is useful, and the lore may be interesting to some people, and they're collectible and stuff, but other than that the buffs and crap are pretty circumstantial.

Maybe I'm just missing something.

The collecting part is probably the biggest motivation. There are a lot of people who love collecting, so monster book would be great for those people. Also, since MS gets very monotonous at high levels, you could just go and hunt for some cards for fun.