If you you have a vocalist anywhere near the ability of Ann Wilson in your band, she will always be your primary focus, and don't ever forget how lucky you are to have her.
-Vurbal
Agree 100%
To be a good guitarist takes some talent, some education, and a devotion to mastering some techniques.
Pure unvarnished vocal talent, however, is a gift from the gods. Be respectful. 
-40hz
As a vocalist, I'd actually disagree. People think it's about innate vocal talent... but I'd go the route that it's a combination of qualities that make those timeless vocalists. Many of these qualities can't be taught... but they can be developed. And many of them are not the classical technicalities - some vocalists are actually known for their peccadilloes.
From Johnny Cash to Leonard Cohen- there are examples all over the place. And how many times have you heard better singers take on Hallelujah... but fall short of Cohen?
Though I most emphatically agree with you about Ann Wilson. I saw her in one performance at an awards ceremony, and initially, her sister had all of the focus, and why not? She was dressed down in all black with a deep brimmed hat that hid her face. But when they started performing, it was like a star had descended to light her up. And this in her 60s? When it's only by nostalgia that I can listen to her contemporary Stevie Nicks at this point. I don't know what she did to preserve her voice, but it seems in all honesty more powerful now.