I think they are doing that because using real images the model changes the face. So that problem is removed if the initial image doesn't show the face
This genereation seems that is getting performance using more power and more cores. Not really an architectural change but only packing more things in the chip that require more power.
Board games have been used in AI since the beginning. They provide a good environment as we know the rules and control them. Also as everybody uses them it is easier to compare different algorithms. Most advances in AI were done in board games. Most probably chatGPT uses lot of those things you think are irrelevant in board games (reinforcement learning for fine tuning the responses with human feedback, same algorithms used in board games).