[The AP Ninja]

This is a veeeery wild guess but take a look at Hideki Kamiya's quote of his let's play of the first Bayonetta:

Speaking of things that were cut, we once had… What should I call her…? “Teenage Bayo”, maybe. It was an idea that would have Bayonetta becoming a younger version of herself. Back then, the magic gauge was totally different. I suppose it was similar to Viewtiful Joe’s. It would deplete when you used it, but gradually charge over time. We tried it that way for a while. If you used all your magic in that version, “poof,” adult Bayonetta would become teenager Bayonetta. She had a ponytail and a higher voice we altered with a little pitch control. She was actually pretty cute. Unfortunately we had to lose her when the magic gauge changed.

Kamiya has recently hinted that he would love to make Bayo 3. The magic gauge greatly changed its mechanics in the second game, and said game revolved around time travel even more than the first one. So maybe Kamiya changes the magic gauge again so that it works with that regression mechanic.