Great singing is a must for bands. If you can sing on key, that's half the battle, but it isn't good enough. Alvin the Chipmunk sings on key, but you wouldn't want him for a front man. Ditto for Pee Wee Herman, Minnie the Mouse or the late Tiny Tim.
A great voice needs passion, warmth, what they call "soul." It also needs strength. I heard one of my new associates sing "Mustang Sally" at our last practice, and it was really good. It was as if he had bass speakers in his throat. He had volume and power. He knew how to "belt."
I read something about singing recently, that said there needs to be a lot of vibration in your nose, vocal chords, lips, etc. There are lots of tones and undertones and nuances that have to be there.
How do you get all of this? If I knew that, I'd be a lead singer.
If possible, listen to the videos and recordings with head phones, unless you have larger speakers attached to your computer. The small, built-in speakers in most computers cannot reproduce the bass or the warmth of the original recordings.
I play bass guitar and string bass in and around Hollister, California.