The teeth are probably what changed her, you're right. I just thought about China Matsuoka who did the same thing and it changed her face a lot. I will not enter into details, but I guess it's because of veneers. It's the fastest way to correct your teeth without have a brace. I had a brace and I had to wear it for 2 years I think, so it's noticeable. But at the end, my teeth didn't look like that, there are no "fake" look as you can clearly see the shape of my teeth.
Now, I agree with you, and that's the mentality in Japan I think (people care less about it), perfect teeth are some kind of a turn off. Of course if you have really bad teeth you should do something, but little imperfections make you special. Plus Ayami, at the beginning, it made her really cute. Yaeba re cute. I always take Chihiro Anai (ex HKT48) as an example. It makes her super cute.
I will try and see if I can be excited by her recent movies. I don't like "fast & furious" sex (lol), where there are no emotion