I wonder if this still isn't in some way a relation to the popularity of the Arabic names among Black Muslim organizations, since many male Arabic names end on the 2nd syllable --
Jamal, Jaleel,
Karim,
Rashad, etc. My guess is many Americans today would view those as "black" names and not realize they are even Arabic in origin.
If you think about the generations up until about 50 years ago, white American men were named
Bernard,
Maurice,
Tyrone. Now, those are seen as black names. So I wonder if this was all started by the influence of Arabic names in the '50s - people unconsciously heard the similarity between the 2nd syllable accent names and the Arabic names, so that the white community gave them up and the black community continued to use them.