Why? It's obvious. For much the same reasons that Rome was hated 2,000 years ago, that Greece was hated some time before that, that Persia was hated prior to that....

That Stalin was hated, that Hitler was hated, that Imperial Spain was hated in the 1500's, and that the British were hated in the 1700's, for example (by the American revolutionaries and many other people).

But you already knew that, didn't you?