SE did, if I recall correctly, add some of the resources required for the next set of monsters that were going be released.
The ingenious part of Monstrosity was that it used resources that were already in game. All the animations already existed and it is unclear to me how much of the TP move information (modifiers/effects/levels) were novel. I think there is a very real chance that they were just exposing resources that already existed.
We know that monsters get certain TP moves at certain levels and that there is a different entry in the monster skills resource dependent on the effect of the TP move (for moves that are named the same but do different things). All the TP moves that I checked at the time had IDs corresponding to a real-monster move with the same effects (as far as I could tell.)
The hardest part of the system (implementation of the actual MON job and species swapping infrastructure) was already done. It's just sad that they failed to complete or motivate it.
Oh well. Now the system exists so daring dancer behemoth can slaughter goblins in buburimu just as tanaka intended.