Well W.C. -As far as the Ronettes go,I can only guess they are going in because of the relation to Phil Spector and his wall of sound (and Ronnie being his wife

).
Sorry to tell you,as the years go on,rap artists will be inducted. I can only guess Sugarhill Gang or RUN~DMC would be the next ones. (I think Sugarhill Gang should have been first,since they were the first rappers to hit the top 40 in 1980 at all).
Marginal talent is in the "ears" of the beholder. Some might agree with you,others not. I do find the Sex Pistols to be the most marginal! :D LOL!