I would say that there are not many AA men who date African women because of the "ignorance factor".
We as amerikkkans have a tendency to not venture out from our comfort zones. As a man in a society where there more women than men, there is no need for us to broaden our horizons. That is to say we do not need to go to a place where we might feel uncomfortable.
Of course I cannot speak for all amerikkkans, I will try to relate a part of my experience.
Although I have not dated sisters from the motherland (yet), I have dated sisters from the caribbean - I have to say it was quite an education. There are distinct cutural differences that come as a result of having grown up in the states. Fortunately, the main sister I dated was very patient with me as I struggled to not put my foot in my mouth as I espoused some arrogant "americanism". I never realized how continental we can be - until I was "slapped" in the face with it. (I didn't even know what plantains were)
I have since immersed myself with all things African and carribean, and I am much better as a result. I no longer assume that all people from the carribean are from Jamaica or
Trinidad. I thank those sisters for helping me to understand them better and indeed myself as well.