I'd challenge your assertion that WWII is considered, at least at any academic level, to be a war 'between good and evil' - indeed, any such definition is an oversimplification. WWII holds a special place in the public consciousness of many cultures, and with good reason, but it cannot simply be reduced down a description of 'good and evil.' Your assertion that Allied war crimes are 'ignored by history' is additionally incorrect. Your question is extremely broad in scope, and to properly answer it would require discussion of public opinion of conflicts following WWII - this is outside the scope of my expertise, so I shan't.

Firstly, to answer your direct question: World War Two, in the public consciousness of Western Europe and the United States if not in academic circles, could fairly be said to be understood in terms of a struggle between good and evil. While the reality of the conflict is naturally far more complicated, the fundamental basis for this public understanding is valid. The Allied powers in Europe waged a defensive war against an aggressive, maniacal, genocidal regime - a regime which brutally murdered millions of innocent people and which directly contributed to the deaths of millions more. Certainly, the allies committed war crimes, but they pale in comparison to the wholesale, systematic slaughter perpetrated by the Wehrmacht and the Nazi regime. While there is poor public awareness of allied war crimes in the Western world, these crimes are most certainly not 'ignored' in academic circles - indeed, there is abundant discussion of them.

To sum up: The vastly different scale, circumstances and motivations of western allied war crimes as compared with those of the Axis makes the poor public awareness of allied crimes, understandable, if unfortunate. While the actions of many allied soldiers were deplorable, they lacked the scale, ideological basis or systematic encouragement that characterised Axis war crimes. The actions of the western allies are judged as a battle of 'good against evil' because, to put it bluntly, one side was attempting to conquer, enslave and murder tens of millions of people, and the other wasn't.