They do explain why in the post. (Still, you may not agree, of course.)
> We are deploying image and voice capabilities gradually
>
> OpenAI’s goal is to build AGI that is safe and beneficial. We believe in making our tools available gradually, which allows us to make improvements and refine risk mitigations over time while also preparing everyone for more powerful systems in the future. This strategy becomes even more important with advanced models involving voice and vision.
> We are deploying image and voice capabilities gradually > > OpenAI’s goal is to build AGI that is safe and beneficial. We believe in making our tools available gradually, which allows us to make improvements and refine risk mitigations over time while also preparing everyone for more powerful systems in the future. This strategy becomes even more important with advanced models involving voice and vision.