The reason for bringing them back was how clinical and cerebral, and less friendly GPT-5 had gotten, leading to a very public backlash.
After this, OpenAI spent a lot of time thinking about personality and customization — leading to GPT-5.2, which now has the overwhelming majority of users.
The previously very popular 4o model is now only used by 0.1% of users.
In their announcement today, OpenAI also says they are making progress towards a more creative version of GPT for adults, having rolled out age prediction earlier this month.
Read more: OpenAI’s announcement, discussion on r/ChatGPT.