You have one very good point. The reason why HP will always only be 'good' and never be 'very good' for me is because J.K.R. couldn't let go of an black-white perspective. She claims to be against prejuicdice (descrimination = werwolfs, mudbloods,...etc) but the way how she is telling the story she is doing the same in the end (rich (blond) people = evil, only one group is the perfect ideal (gryffindors) others are automaticaly bad (slytherings),... etc.)
She never create a logical self-consistent theory about magic/ the so called dark magic/pure-blood believes and how and why they spread,...etc. which would be important for the story. I'm going so far that it is very insolent copying directly from a cruel phenomen like anti-semitism with such a long complex history in such plain way.
Most people who are doing 'evil' actions are not conscious they are doing something bad but think they are doing something good. Only because someone is a murderer doesn't mean he cannot truly honestly love his family (which makes it bullshit that more 'normal' deatheaters with families like the Malfoys, crabbe, goyles,...etc. cannot make a patronus but a mean person like Umbridge can). And she totaly lost me with the fact that she portraied CHILDREN from the beginning as onesided good (gryffindors) and onesided bad (slytherins), ignorant nerds (ravenclaw) and lovely loosers (huffelpuff). It's clearly pure purpose.
Also the claim murder is inhumanly is nonsense. Gladly it's not so common and neccesary anymore in modern days but for thousands of years it wasn't unnatural for the human race to kill each other even if it's "only" for power/egoistical motives. It's also nonsense some claim animals aren't like that. Some races aren't some clearly are more agressive even only for fun with conspecifics like orcas, dolphines or orangutans.