If it is still not clear (wasn't clear to me):

Let's say that there is only 6 heads, 6 bodies in VV.[lets say 15KB] (36 possibilties)

Now let's say you want to add black people. 12 heads and 12 bodies. [30KB](72 possibilties)

Hey! we wasted 30KB of space for just 72 possibilites!! If we don't add black ppl and add 6 white heads/bodies

12 heads and 12 bodies [30KB] (144 possibilities)

Now if we still go with Path 1, we need another 6 heads and 6 bodies if cross breeded.(18 heads/18 bodies] 45 KB [108 possibilties]

18 heads and 18 bodies white = 324 possibilities and 45 KB

So you get my point? Same size, but if we make half another skin tone it will make the possibilties over 50% less! Not to menction how much programming needs to be done.