I realize this isn't the same thing as your point about images as part of training data, but just flagging it in case anyone isn't aware: Claude Code lets you copy and paste images into terminal. I've been designing a "universal history simulator" game for use in my history classes lately, and it is really helpful to be able to make a mockup of a ui change I want and then paste it in, rather than trying to explain it verbally. Also good for debugging graphics issues.