It's also not spoken word, there's so many underground rappers with great lyrics who just can't cut it cause they lack all the intangibles. Voice, flow, cadence all these things play a huge part in making a great rapper. Even a dude like Talib Kweli who ended up having a lot of success couldn't quite make it to the upper echelon in terms of commercial success because he had a weird voice and a downright bad flow, great lyrics though. And he only made it to where he was cause of Jay saying, "if skills sold truth be told, I'd probably be LYRICALLY Talib Kweli."
Biggie
Pac
Jay -- thrived more because of flow and confidence than voice, but still a good voice
Nas
Redman
Jada
Styles
Beans
Method Man
Fab
The list goes on and on of good to great rappers who at the very least have an extremely distinct voice if not a great voice. Never heard anyone imply that saying a rapper has a good voice is in anyway gay.