I don't think it can be denied that in the 50s and 60s many black artists were exploited or not given the same opportunities as white ones. The problem to me is when that principle is applied in every case. Then it gets especially muddy when applied to UK cover versions. Plenty of white acts had their records covered in by British acts and released as singles in the UK - off the top of my head there's Billy Fury's cover of Tony Orlando's "Halfway to Paradise" and Susan Maughan's "Bobby's Girl", originally by Marcie Blane. These UK releases were huge hits and totally wiped out the chances of the original artists getting a look-in in Britain. Surely the fact is that UK based artists were better placed to tour and promote the records than someone in the USA, so the colour of the original artist loses some of its relevence.
The example of Timebox quoted earlier is a really interesting example, as their biggest hit was a cover of an original by white Italian Americans. Were the Four Seasons being exploited or was this secondary exploitation of black people because some people in the UK consider some Four Seasons records to be performed in a style that apes black music?
You also have to take into account that all this talk about 'having soul' is often more important to fans and collectors like us lot than the artists. If you hang around with professional musicians you'll find that most of them are purely interested in whether it's a good song or not.
And how about that Otis covering "Satisfaction"
Yikes!
ps
Not keen on either version of Go Now as the song doesn't do it for me, but Georgies version of Sitting in the Park tops Billy's in my book.