(I’m sorry, this turned into meta) I admit that Mimi can seem ditzy at times, but I think it’s important to note that her crest is Sincerity- even though the things she does may seem out of place or inappropriate at times, it’s important to note that she does them only because she is making a genuine effort to be kind and helpful to her friends.
Take the scene above for example- the Digidestined have just finished a difficult battle with a new enemy and they feel frustrated because there is so much about the situation that they don’t understand yet and they’re not sure what to do from here. Tensions are obviously high-
Enter Mimi- she embraces Palmon and gives everyone a warm greeting, which garners this response:
Everyone is smiling, obviously glad to see her; Mimi’s presence is like a breath of fresh air, and it’s a relief to all of them.
But then she does one better- she brings gifts for everyone (Digimon included; we all know how much the Digimon like food lol) and completely changes the atmosphere surrounding the group.
In less than 3 minutes, Mimi managed to relieve the tension within the group (albeit temporarily) and change the mood from heavy and serious to lighthearted and friendly.
Mimi’s pure heart has such a positive effect on those around her; as the Digidestined often undergo difficult and stressful ordeals, Mimi provides a childlike kindness through simple (seemingly trivial) actions that I would not reduce to “being a ditz”. As someone who personally ships Koumi, I think that this is important with regard to Koushiro seeing as how he can easily overwork himself and forget to relax and enjoy the simple things at times, so Mimi could help him with that.