All I'll say is that I've never seen this kind of joke taken that far. For example, take Great Teacher Onizuka. In comedic scenes, this anime distorts the characters' face, going from anime faces to "realistic" Japanese faces. But even there, they're still recognizable as the same person.
In Fujimiya's case, it's not just a distortion. It's completely different face. A different person. Hence why the gag didn't land with me, because it's so cheap to just use a completely different face. It'd be funnier if she was recognizable, but way uglier. I mean, ffs, I thought her younger self was the younger version of the uncle ...
We don't need to make this a long debate, but I don't understand why I cannot express my opnion on it without someone attacking me.