Mii are suppose to be very cartoony and goofy, and I can appreciate that design choice. That being said Nintendo Land shows how Miis can be improved. Nintendo Land asthetic changes to Miis that should be standardized:
The shiny plastic look that makes them look like toys, it's perfect with the design choice. The ball and socket feet rather than the stubs. Clothing that looks like clothes and not painted skin. Texture patterns. Finally give us more than changeable hats, give us those nintendo land costumes.
The Miis have so much potential and Nintendo Land really is a game that shows that off quite well.
Oh but this is besides the point, no never would I want my Mii to be the MC. That being said I wouldn't be opposed to have it as an option in a console pokemon game. Especially if again they went with the Nintendo Land route in terms of artstyle.
I've got a quote that embodies you perfectly, but it's seventy-three posts long, has a few massive flowcharts, and lots of Xion-KMA to Me