Well the idea is based on opinion, so there's really no true or false to be had. Some people view things differently then others do. Everything from Attraction, to Stigma's to perceived Characteristics are all based on someones point of view. It just so happened that the majority of people participating in this particular incident preferred the redhead version, and the blond stigma toward her being seen as less of a fighter may not have even been a factor.
After all, there are plenty of people that see blondes as Evil and deadly as well.
With character design it doesn't really work like that, though. Not entirely. Everything from hair color to bust size to the name of the character is typically given because of what it "represents" and how it "suits the character". Granted, in this case, they were mostly going for a let the audience decide kind of deal.
But you had the prime forces against that design were a feminist blogger who claimed that the blond Shepard "destroyed the character" for her by making the character look "like a bimbo". Also, in the voting process itself, the comments were flooded with people bashing that specific design because it wasn't badass and, again, "looked like a bimbo".
I'm not upset by the choice, overall. There was a vote, and a design won. That's the nature of voting. And I've never heard of anybody using the standard design, anyways. What bugs me is what seemed to have been a prevailing assumption that she couldn't have been a tough soldier/heroine type and
been a blond character. An issue that I think was actually pretty well addressed in the Penny-Arcade comic based on the controversy.