Why is every black person in this movie so light skin except for Bill +

Me, not being obsessed with skin color, wouldn't care if they were purple.

I personally thought Kim was medium brown but why does it bother you that badly? The actors did well.Remember,there was once a time when minorities were not even allowed in the film industry at all (ex: black-face white actors playing blacks in he early days and later,overly tan white and greek actors playing hispanics, etc).

Sorry they didn't cast some dark actor like Wesley Snipes but, as you said, its a director preference.

There is also the possibility that no dark actors auditioned or that the lighter actors just out-performed them

I feel you.

It's really interesting how everyone had the same skin tone.
Like they didn't even go the route they did in the Cosbys where they tried to get children of varied skintones.

It's definitely a stark contrast and things you notice.

Colorism is a helluva drug that a lot of folks in Hollywood have been enforcing for a while.

It would have been nice if Cosby's character's late wife had been a white woman. The actors playing the three children were all clearly bi-racial.

It annoys you cause you're a racist moron. I'm white but I never thought about it when I watched the movie I just thought it was a fun movie, must suck to be miserable

I would say they are 'lighter skinned' but not light skinned. Black families can have a variety of skintones. Latoya Jackson is naturally light while most of her siblings were quiet dark.

Because Bill raped a few white women and they got impregnated by him

Cosby always seems to hire child actors that resemble his family members (Daughters) who are lighter skinned.

When there's no more room in Hollywood, remakes shall walk the Earth.