I Cor. 9:22 To the weak I became weak, to win the weak. I have become all things to all men so that by all possible means I might save some.
Nothing wrong with gospel rap and R&B if it's done for the glory of God. If it's drawing in young sinners, if souls are getting saved, if the youth are listening to lyrics about the gospel (regardless of the beat) instead of "gang/thug life" lyrics, that should be a good thing.
Now, I know you can't enter the Holy of Holies with gospel rap, but that doesn't mean there's no place for it. God has gifted many artist with a wide variety of styles to minister to people on all levels in many different areas of life. Gospel rap may draw the youth in, but that doesn't mean they'll stay on that same level.
Learning classical is good but it doesn't make the music any more holier. Being strong in theory, scales and chords is good too, but that doesn't increase your anointing. If your love for God is your motivation for what you do, He will give the increase.