Magia Exedra launching has reminded me just how deep of a rabbit hole I can fall into with Puella Magi Madoka Magica stuff, and I've been chewing on a lot, but I want to present a conclusion I have come to.
You don't really see a lot of Mami Tomoe in the original series for... Various reasons, and that means that it's quite hard to get a read on her personality. Obviously there's stuff there, but you need to really get stuck in with her. Side materials and spinoffs actually give us a great chance to see more of her.
They give us a great chance to understand that Mami Tomoe's fundamental character is "what if Inspector Javert was a 15 year old anime magical girl?"