I don't agree with most of these rules...because a lot of the ships actually make sense, wether they are yaoi,yuri or hetero...why mess with it...
Hetalia is a satire...historical satire....but it also leaves room in the fandom for what ifs...hence Cardverse or Omega verse....or different human alternate universes because let's face, even as a huge fan, I can see the two demensional limitations. Not everything is about history... Sometimes it is about seeing how much deeper you can take the character....for example...I am crazy about America, but can we actually develop a more rounded Alfred f Jones, without ruining him? I want explore development , not copy a satire, that I do love.
However, I agree with six -ten....originality is vital...bias sucks...and I believe if you are writing something...you should know what you what you are writing. Honestly I like things to make sense, but sometimes moving away from a historical point of view to a more. Humanistic point of view makes more sense...especially if you are reading character driven stories.
I do hate cliches ...or stereotypical views that border on being racist.
Character development it great. I really do enjoy seeing it used, especially in fanfics.
And right, I realize that not everything people write will be based off History. I say that because the characters themselves, personality/reactions/etc., are based of Historical events.