It's purely psychological on the part of the duck egg haters.
My sister is the same way. I fed her all kinds of duck eggs last winter/spring/early summer while I was getting duck eggs. She had them scrambled, fried, deviled, in egg salad, hard boiled, and in all kinds of cooked dishes like quiche and chiffon cake.
Had I told her she was eating duck eggs, she would have had a hissy fit.
Not knowing, she didn't have a clue.
In a blind taste test, I doubt that one person in 20 could tell the difference between a fresh duck egg and a fresh chicken egg. Now, between a fresh duck egg and a stale, grocery store chicken egg, of course the duck egg will have a more pronounced flavor, not because it's a duck egg, but because it's fresh, and probably also because the duck, if it came from a backyard flock, probably had a better and more diverse diet than a battery hen from some Iowa commercial egg operation with half a million hens.