Honestly, a magical instant-outfit device would be cool whatever the context.
Shion getting to have fun and enjoy "normal stuff" that friend groups might take for granted is nice, though. Ayame getting the same is a clear upside as well, but even being lonely, he has his Hero Stuff to fall back on as a basis of mental support. Shion thanking him here was nice to see--reinforcing that whether it's Ayame or Ameme, she values that friendship greatly. (And that's great--because it means it's not just the Magical Girl Factor, but the person behind the magic as well that she treasures. Puts Ayame's mind at ease, that way.)
The new MG should be interesting. Especially given the character design--kinda feels Brat Energy-ish, though that's merely an assumption based off other titles' character designs. If she's not super annoying or aggressive, perhaps this signals an expanding of Ayame's and Shion's friend group. Or, a rival for Majeri (or, perhaps in a different sense, Shion?) could be the angle. Will have to wait and see.
Thanks for the TL.