He's right, it would be nice to have some darker skin tones. And don't say it'd be too hard -- you use generative AI in your work, so you don't get the leeway projects done with human labor alone warrant. I'm not saying you don't work hard, but when the work is partly done with clankers and you receive financial benefits from the product you don't get to claim it's solely a passion project.
So for the sake of your customers, please add more base customization -- brown and black skin tones, in particular. It won't be as easy as typing a prompt into PlagiaristGPT, but it's still simple in comparison to many of the requests you are given.