For me, the main frustration has been that Google has its one keyboard (Gboard) for latin languages and then the Japanese IME as separate keyboards. I use English, French, and Japanese keyboards and switch between pretty often, but it's a bit of a pain.

There's noticable lag when switching keyboards that seem endemic in the model of "multiple app keyboards", whereas a more integrated experience would benefit some

Agreed that the "Play Store" model is better for consumers on phones that don't get updates (been there). I hope they try to pull stuff into the core project as well, though. Kinda sad to see Android becoming what people always thought it would end up (a Google-centric venture)