Number one is not just the "vocalist", but the "Frontman/woman" It's not just about having a great voice, you've also got to have a talent with people and charisma. Good examples: Mike Reno from Loverboy (great story teller), Peter Furler from Newsboys (constantly keeping the audience involved and engaged), Robert Plant (huge charisma), and very many more. All very talented vocalists, but there are literally millions of great vocalists. These people took their bands places they couldn't have gone by "being" the front.
See also Joey Ramone, Mac Powell, Siouxie Sioux, Iggy Pop, Annie Lennox, Tiffany Arbuckle Lee (Plumb), David Bowie, Alice Cooper...lots to choose from. Without interaction with the crowd, it's still possible to be great, but it certainly doesn't hurt.
2) image
3) songwriting
4) musicianship
That's how you make money at music.
Now, to have fun in music, change that order to 4, 1, 3, 2. You can have fun playing with a bunch of guys that are great musicians writing decent songs. The voice becomes a lot more important than the charisma and image becomes nothing.
If you can find a group of people to play/sing with that can have fun and make money, consider yourself one of the luckiest people on the planet.