Mixamo character are so ugly...

What was the reason for making them so cartoonish and ugly? You can always distinguish a mixamo character by it’s uglyness

Model your own characters then, rather than use a procedural application that’s meant to be used to create a starting base mesh?

Not truth. Base doesnt mean ugly. Look at makehuman - they are good. What prevented mixamo from making good characters? What? Some guy like you who thinks that base characters MUST be UGLY?