(There are spoilers here.)

I have tangled feelings about both Flip Flappers as a whole and its ending, feelings that I'm still sorting out. However, there are some aspects of the ending that I'm completely behind, and one of them is the show's perhaps odd decision to spend most of the first half of the last episode on a knock down, drag out fight with Mimi when Cocona and Papika had already neatly punched her monster out at the end of the previous episode. As spectacular as all of the fighting might have been, was it really important or necessary?

My answer is that yes, it was, or at least it felt that it belonged to me. To put it one way, it would be nice if you could get your over-protective mom to go away just by you and your girlfriend telling her to buzz off, but life is not that nice. Getting your overbearing mom to ease off generally requires a big screaming argument, although this is usually delivered by words, not you and your girlfriend beating down dark mom's monsters and eventually her more or less directly. But this is Flip Flappers, so this particular psychological point was delivered through some spectacular fireworks.

(In the end it wasn't just this fight, of course, and it never is. Dark mom Mimi had to come around, not merely be beaten down. Beating people up doesn't generally change their mind, and Mimi had to have her mind changed in order to really resolve the situation. Multiple things ultimately contributed to this change of heart, not just Cocona and Papika, and I feel that even Dr Salt wasn't quite as completely decorative as he looked. His presence mattered, even if he didn't actually do anything except stand around.)

Mimi's possessive over-protection of Cocona was a pivotal development (as was Cocona's willingness to accept it), and disposing of it casually and briefly simply wouldn't have felt right. It and other unresolved issues around Mimi needed to be resolved with enough effort to make the result feel earned.

PS: One of the things Flip Flappers is about is external representations of internal psychological struggles and issues. See, for example, this discussion of the pivotal episode 7.

PPS: Yes, they're girlfriends. How much more on point does transforming under their own power into a matched set of armored wedding dresses have to be? Flip Flappers may not always come out to say things out loud, but it's not beyond hitting us over the head with them.