Their stock price is currently suffering because of how poorly iPhones are doing in places with real competition (i.e. China), the iPhone 16 when put side by side with Chinese phones just makes the iPhone look like a cheap knock-off. Even 90hz would fix most of these problems (and the panel is more than capable of it).

They're fixing it on the iPhone 17 because of the above reasons, but it shows how badly their market research teams are doing that they even remotely thought it was acceptable on the 15, let alone the 16.