I think OpenAI and all the other chat LLMs are going to face a constant battle to match personality with general zeitgeist and as the user base expands the signal they get is increasingly distorted to a blah median personality.

It's a form of enshittification perhaps. I personally prefer some of the GPT-5 responses compared to GPT-5.1. But I can see how many people prefer the "warmth" and cloying nature of a few of the responses.

In some sense personality is actually a UX differentiator. This is one way to differentiate if you're a start-up. Though of course OpenAI and the rest will offer several dials to tune the personality.