In part, because historians & philosophers have generally castigated the Allies for not being more diligent in their denazification efforts. Morally, of course, they're right: people like Wenher von Braun were very likely guilty of crimes against humanity, and very possibly should have been hanged (he wasn't, of course, and as a result we got to the Moon). In my late-90s education this was all taught as almost unmitigatedly bad thing; the general belief was that we should have done the Right Thing, not the Pragmatic Thing.

Our experience in Iraq indicates that perhaps the Pragmatic Thing can also sometimes be the Right Thing. We might have been able to avoid a lot of injustice with a relatively small amount of injustice.