It is true many black guys have big cocks. But I have seen some black guys have normal size or small cocks.
The gay world is a cruel world. Most gay guys only like young, muscular guys with hung cocks. I understand it is personal preferences. However, what we can do is not to act like a racist asshole by adding "No Asians" in profiles. Image you are a black guy, and see someone's profile says "No blacks". What would you feel? You may say in profile "Prefer whites, blacks, latinos" instead of "No Asians".
I have some white FBs, and they all into Asians. Of course they are not exclusively playing with Asians only, but at least they have open minds.
To answer the question above. If you have a choice to be a 25 yo man, you need to think where you are. If you are in Asia, maybe. you better choose to reborn as 25 yo Asian, instead of black. So nothing is set as rule.