As an European, I still prefer the freedom to have alternate App stores.
Yet, I still don't see a reason why they don't provide the same app to all customers since it's allowed by Apple, aside from greed or something like that.
Either way, let these developers enjoy their small time of fame, because as soon as RetroArch becames available, a lot of these emulators will be left in the dust ¯\_(ツ)_/¯
I only use RetroArch on PC, so I don’t know how it works on iOS, but I will assume will be identical to the console versions, which already have all the cores included on the emulator (on PC they are downloaded individually).
I wouldn’t call it just a front end, it’s much more than that, and it has a great integration. Also the devs seem to focus a lot on the emulation accuracy.