Why is it ok to say

"I'm glad you married a Black/White man, i've always wanted mixed race granchildren"
"gay men make the best Singers/Actors/models etc"
"Minority group X is better than Majority group X, in field Y"

But not

"I'm glad you married a White/Black man, i've always wanted purely White/Black granchildren"
"straight men make the best Singers/Actors/Models etc"
"Majoirty group X is better than Minority group X, in field Y"

In fact, it used to be the other way around. Because social change happens gradually, at what point was there equilibrium from which the scales would sway the other way?