I'm not saying it's entirely reasonable to lay all of that hate on the Queen's feet. But just as she was a symbol of hope and progress to some, she's a symbol of a deeply evil, globe-spanning empire to others. I don't think you can give her credit for the good without accepting at least some credit for all the harm that happened under her watch as well.
If we're expected to be understanding to the people grieving the loss of a celebrity, surely we should be a thousand times more understanding to all the people who are angry at far greater losses caused by the British Empire.