The monster AI was one part of DM's codebase that I was never really able to figure out, even with the help of the DM Encyclopedia and the reverse-engineered CSBwin code. As a result, most of it was generated trying to match the look and feel of the way monsters in DM behaved, although I think that DSB's monsters are, generally, quite a bit smarter. This change was well-received, so I've been going with it, making further incremental improvements to the monster AI over the course of DSB's development.
In the next iteration, monsters will have even more quirks and fun features.

Each monster will have an optional flag that allows it to duplicate the behaviors and special attacks of the D&D monster it's a rip-off of.

Screamers, Rock Piles, and Golems will now make use of flanking, feints, and other sophisticated tactics that nobody will notice because of how slowly they move.

More monster-to-monster interactions will be handled. For example, Animated Armour meeting up with Rusters will have a humorous but realistic result.

Vexirks and Dragons will occasionally randomly blow themselves up with a fireball, because, really, we've all done that and why should they be immune?

Characters will have a hidden stat which controls how frightened of them monsters are. (Mophus's will be 999)

Lord Chaos will still find none of this funny.