1 Talent is only worthwhile if you practice. Just because someone has SRV like speed or tone doesnt mean they have his fluidity or familiarity with playing what he feels. It seems to this newbie that musicians in a band (singers included) should come to practice having practiced. Unless you are a pro who has played or sung more than god and don't really need to do more than brush up, some woodshedding is in order always.
2 Electric equipment cannot cover for your lack of preparedness especially for vocals as we have to adjust for the amplification. If you can't unplug everything and perform the song with feeling and really enjoy it, why would anyone want to hear it? If a vocalist can't adjust so that the feel, pitch, tone and warmth translates through the mic and out the speaker it sucks as well. I appreciate the finger in the ear technique, I use that a lot, but I encourage singers to just do the one ear, multitasking is important and listening is more so.
3 Vocal specifically speaking. We walk around our lives using our instruments every day but not for singing. We develop a sence of self and how we represent ourselves to others from a skewed point of view. Singing is very different than speaking and needs a lot of work to get any good. What we vocalists hear on the inside is very different from what we sound like to the rest of the world. This is very difficult to get used to and why many of us hate the way we sound on recordings cause it's us but not the us we know and love, very creepy.
The closest metaphor for a vocal instrument would be taking all the frets off a guitar and playing only one string but you have to do it inside an organic booth that has adjustable acoustic characteristics. You have to hold these correctly for your tone while shaping it for the expression of words. You then get to play for people outside the booth and adjust for the accoustics or amplification in the greater chamber. On top of all this, pitch, rhythm and feeling while telling the story or reciting the poem are our responsibility as well. Not to mention remembering all the words to 300 or 400 poems and stories WITH the appropriate band specific breaks and changes. This is where the metaphor just gets silly but I hope my point is still there.
Singing is more complex than many instrumentalists or singers for that matter seem willing to admit. Practice and listening to yourself on some recorded media are essential to getting any good. Then you might just discover that you really don't like what you have to offer and should prolly take up an instrument instead. In the meantime, get a thick skin to negative comments and use them to improve. Get a thicker skin to positive comments and use them to improve.
All of that being said, there is no excuse for not practicing. Wow that's a lot, sorry hehe.