A singer is usually the most important performer in a rock or pop band. Rock and pop music is intended to appeal to people who haven't devoted a lot of time to studying the mechanics of music. It's the words that connect to these people.

Vocals are key to 'popular' music. There are only a handful of instrumental 'hits' -- unless you go classical-on-me. One-step further -- I am always in awe of Bob Dylan who's lyric and style overcame a rather non-skilled musical voice. His poetry and political-conscience overcame his vocal and musical skills.

Also, it helps if the female lead-singer has a great body. Better if she wears revealing clothes and grinds-her-hips while she sings. Maybe you can get a contract with Disney .........

I think that if you have a decent vocalist, whether they be screamer or not, it is an instrument just like anything else, and it should not take over the rest of the music. Have you ever been listening to song, and thought, "Man this song has a great back ground, if only the vocals were a little more mixed in better. It works the other way though, as well. You have a lead player, that plays all over the vocals, like Santana, and sometimes it works, sometimes it's more like "Okay, we know you can play."

If someone cant understand the emotion put forth from the instruments themselves, the singing definitely does that. It tells a story, and helps relate things to the listener, etc. Sure, the singer is usually the one getting the most attention, but its not like the people playing the instruments are completely unappreciated.

I think it depends on the band for some the Vocals are important others its all about guitar works, there are a few bands that seem to point out the bass and drummers, but I find its mostly the singer /guitarist which is crap becuase you need all the pieces of the band to sound great IMO