Personally, I figure the Nazis get the attention quite simply because they very much demonstrated modern industrial civilization gone wrong, how the techniques deeply integrated to Western societies can with frighteningly little modification be employed for industrial mass murder.

A kind of dark mirror, which is remembered so that people do not forget why the restraints of sanity and ethics are a vital companion to technical competence.

Side note: I understand the German military was quite adamantly opposed to the whole death-camp thing, on the purely practical grounds that it seemed pure lunacy to them to tie up so much industrial resources and transportation capacity direly needed for the war effort for the sake of such rather pointless project that produced nothing of value. A fair few other agencies were similarly opposed on pragmatic cost-efficiancy grounds.