Personally, I don't like shading my skins. It's more of my style to keep them cartoony.
the only thing I do shade is the hair, and that's only noise added with Gimp.
I think overshading is not good in my opinion, because it takes the minecraft straight out of minecraft, where everything looks simpler.
My newest skin for example, is a well made scientist. He intentionally has no shading except for the hair. I just want to bring a different side of the community out, by creating simple skins that have nothing added in, like popular TV characters, or backstories either.
People can make what they want to make out of him. Shading just detracts from "Oh hey! I can turn this skin into a roleplay character!", because your mind will maybe switch to, "This looks realistic, so I have to act that way on the server".
and it's true that Overly shaded skins get more diamonds. It's a shame really.
People who don't shade deserve as much attention as a person who gets 42+ diamonds for an overdone character.
this is the end of my comment.