Oda brought Big Mom to Wano to:
- Make her and her crew look like shit for getting kicked and owned by King and Marco
- Make her crew look stupid by being lost in the ocean for 100 chapters
- Make her lose her memories and go into "O-lin mode" and fuck around against Queen
- Make an alliance with Kaido that did NOTHING, it's getting taken down a few hours right after being made
- Maker her have a "mothering mode" where she helps her enemy in the middle of an invasion
- Maker her get defeated by Law and Kid without them even using Haki, just pure Devil Fruit powers