It really is a shame too cuz I do like this pack. Underwhelming and buggy as it is, it's still a something that I've been looking forward to since day 1. I feel like this might have done better as an expansion because it has a lot of good ideas that, unfortunately, feel like they couldn't be fully fleshed out in just a game pack.
I don't believe for a second that kids were exempt because of some arbitrary moral standing (like that asinine doghouse excuse). Vampires I can slightly understand. But spellcasters? Come on! Kids use magic in fantasy stories all the time. One of the most popular fantasy stories in the world is about a bunch of kids who go to school for magic!
I think they just either didn't have time to copy the spellcasting animation onto the child models and restrict their spell access (I've been meaning to ask the guy who did the child magic mod for TS3 how long it took him to do that), or they just didn't think it was important enough. I wonder if that would have changed, had this been an expansion instead.