It strikes me as something that would have been a huge elephant in the room. The Nazis advocated for the position that blonde, blue eyed individuals were the most racially pure, and the man leading the party had black hair and brown eyes. Was this ever addressed, at any time, or did everyone pretend like they didn't notice?
The idea that blonde hair and blue eyes were the epitome of Aryan purity is actually a major oversimplification of Nazi propaganda.
It's true that the blonde haired blue eyed type was often featured in propaganda posters (although even then, not exclusively), but it was not promoted as literally the most perfect physical type.
To add to what /u/daedalus_x has said, blue eyes and blonde hair was an ideal, but German propaganda actually tended to downplay physical features when discussing the ideal Aryan. A Hitler Youth booklet called "Faith and Action" says: "Race means to be able to think in a certain way. He who has courage, loyalty and honor, the mark of the German, has the race that should rule in Germany, even if he does not have the physical characteristics of the “Nordic” race. The unity of the noble soul and a noble body is the goal to which we strive. But we despise those whose noble body carries an ignoble soul."
Hitler's actual definition of 'Aryan' changed based on what was politically convenient. Originally it was "white, non-Jewish" but it became necessary for him to add Slavs to those who were white but not Aryan. The lack of a specific definition allowed him to change it when it was convenient, as was the case in Yugoslavia with the Serbs being considered the "most Aryan" in the region... until a Serbian anti-Nazi coup forced him to declare the Croats the most Aryan.
The idea of Aryans being blonde-haired and blue-eyed was actually borrowed from contemporary anthropologic history; 'Aryan' was the then-current name for what we now call (Proto-)Indo-European. HG wells discussing the Aryans giving this exact description of them in his A Short History of the World, from 1922 as well as later revisions). Link
So, that's where the idea comes from. Obviously, it's somewhat muddled with the rather peculiar view on the existence of 'races' at the time, but that the state of (popular) science at the time. Now, bizarre retro-Romanticists like the Thule Society, one of the ideological influences on Nazism, borrowed elements from then-current popular science to fit their esoteric ideas of a superior god-like race of men, including the name 'Aryan', presumably to give it more authority. Like with everything the Nazis did when it came to ideology, they just picked what they liked without caring too much about coherency. They might as well have used 'Atlantean'.
Now, obviously Nazi ideology was distantly removed from anything anyone could call science, but there was a distinct element of racism present in the Nazi ideologies that was also present in the scientific ideas mentioned above; this connection was obvious to anyone, which is why the collapse of Nazism also caused to collapse of scientific racism soon after that. Link
This has worked out well for the most part, which is why people these days can hardly believe that the idea of blonde-haired, blue-eyed Aryans was ever a legitimate scientific theory and not just something the Nazis thought up (which they did not, as said above).