Aggie's role should have been Periwinkle's role

Periwinkle did come off as the Aggie replacement in this movie and Marnie even states how she reminded her of Aggie. Aggie's role in this movie was nothing more than a cameo that with the blink of an eye you could have missed her. I don't know if it was the writers' choice to make Aggie so absent or if it was Debbie's choice not to have a big role but if Debbie was up to a big role then they should have made Aggie the undercover agent that was after the dominions and a professor at the college. Splendora could have been her mother or something. It never did make sense why Aggie wouldn't still be Queen of Halloweentown at this point in the present if she was such a thousand years earlier. Why did she just stop being Queen?