The problem with using AI to "complete" a drawing vs a paint bucket tool to fill in a solid area is that AI is actually stepping into the creative process and cutting out a human.
If you look at the below example, it's not really fully Cedric's drawing anymore. If another artist drew the final image, they would probably deserve a credit. Decisions about shading, paint mediums, light sources, textures have all been made that aren't in the original drawing.
It's like you drew a storyboard and handed it off to another artist to complete the final render. That's just not the same thing as using a paint bucket tool to quickly complete the final render yourself. If you're an artist who doesn't enjoy inking and coloring then your art will have a certain unique style (which I think it does) reflective of these strengths and weaknesses. If you want to draw something more colorful, it will require you to learn more about color, practice, and grow as an artist (which is also good). But outsourcing to AI means that your work will not really be yours anymore.
The connection to Cedric the unique person created in the image of God will be lost and instead the machine will step in and make it "better". The sketch on the left contains a lifetime of practice, refinement, frustration, joys and inspiration from the creator. The image on the right has none of that.