Then their engineers are not very good, because all the improvements now come from Google (Night Sight, 3D gestures), Huawei (5x zoom), Samsung (60MP sensor), Oppo/Xiaomi (front camera behind the display) and so ones.
Without commenting specifically on the features you mentioned, I'll just observe that being first to market with a particular feature doesn't mean that you have the best implementation of that feature.
So either Apple is a class-leader in R&D or they wait till others have cut their teeth on tech before adopting it, thereby minimize their costs but are also not leaders in R&D and dont have others stealing from their work. Which is it?