Here's the thing with singing... Someone mentioned that the key to good vocals is passion, pitch and pocket. Yes, but that's not all. I'm gonna use American Idol to help illustrate my point. There are many technically great singers that have made it far on AI. But just because someone can "technically" sing, doesn't mean you want to keep hearing them sing, or that they move you in any way.
Think of someone playing a passionate, well tuned and timed & technically correct, (passion, pitch and pocket) guitar melody on a cheap guitar on it's bridge pickup, with the amps treble and mids cranked, and bass on zero... who's gonna want to listen to that for long. Tone is huge, and not far behind is style. Vocally, you're either born with good tone, or you're not. Simple. Style, you can work on, but it's usually innate. Good singers always find ways to separate themselves from others stylistically. Phrasing has a great deal to do with style. Combine this with technique, and you've got talent. Emotion/passion are always needed, that's a given.