I'm mostly just annoyed by how oblivious we're supposed to believe that Harry is -- not just with Ginny, but with tons of other characters that he 'just hadn't noticed'.

The wizarding world has an archaic government, an emphasis on purebloods, and Umbridge in a position of power. What more could go wrong?

Not just an emphasis on purebloods, but an accepted system of slavery (house elves). Plus, the fact that werewolves are classified as dark creatures (or whatever) means that some people are second-class citizens because of something that they can't control.