The biggest thing I like about the Game Character Generator is, once you have created a character, you can save the exact character layout. This is incredibly helpful if you need or want to go back and change a few things, like the armor the character is wearing, because the layout will have everything you did. I've had to do that for a game I wrote. So you don't need to create the character from scratch again.
Also, for creating NPCs, you can rapidly create dozens of similar characters by asking the tool to vary, say the shirt, eye and hair color through permutations of each. This can help populate your game world.
The only thing I wish it did was create the Faceset and character sprite at the same time from one template, but there are so many pieces I imagine that's almost impossible to coordinate the two.