Modding : Why does Cast function NOW requires the skill in tree ?

Hi, since last patch (or maybe the crucible DLC, I don’t really now when it was done) the Cast function used in conversation requires the NPC to have the skill in his skill tree wich means modders are limited to only 17 available slots per NPC.

Was it intentionally done because there were some bugs with creatures castings skills they shouldn’t or do you think you can bypass this requirement in a next patch to revert like it was before (no limite to the skills the NPC can cast)?
Or maybe it was because the Cast function does not have a level for the skill and now the skill is cast according to it’s level given by the NPC skill tree ?

Thank you