At a recent service I was reminded of how thin the line is between leading prayers for the congregation, and praying on behalf of them. It doesn't help that the line is very changeable based on the individual and their mood that day. Still, I believe that a proper understanding of the difference is one of the keys to a successful congregation.
I've often had the feeling, especially in congregations with a strong cantor, that I was being prayed for. This is not to fault the cantor; most professional cantors are quite good at what they do; they're so good, in fact, and pray so well on my behalf that I'm not sure I even need to be there.
Just to illustrate that fine line I mentioned, I like my services full of music and song, so clearly getting rid of the cantors would not be the answer. And it's not only cantors that cause this feeling; they are just the most common, and most noticeable, cause.
The music hold another issue; if the melody is not singable, it is very difficult for me to get involved. Some people find some melodies so inspirational that they meet their spiritual needs by sitting and reflecting while they listen to it; I am a much more active prayer. If I can't sing along (and I have a lot more singing experience than most congregants, so you have to really work at this one), I lose interest. This does tend to be a problem of, and for, the cantors. Understandably so; they encounter so much incredibly beautiful sacred music, and want to share it with the congregation. That's laudable, but can also change it from a prayer service to a concert.
I also believe the prayer book plays a large role in it. Despite being a staunch non-traditionalist, I love the traditional prayers, and traditional melodies. I feel they have gained a certain power and familiarity over the generations of their use (even though some of them have been around for many fewer generations than we'd expect); take those away, and you're left with some random piece of poetry or music that I will like or dislike. If I dislike it, or even like it but find it lacking in "meaning", the service becomes a lot less intimate, a lot less personal. If all we're doing is reading poetry from some book, well, you can do that just as well without me.
Prayer leading, by contrast, works a lot like song leading does at camp. You, the song/prayer leader, are not the star; the congregation is. No one came to hear you pray/sing; they came so they could do it. Your job, as leader, is to set the key (one that most people can hit), hold the tempo, and use a loud, clear voice so anyone that forgets the words can pick it up from you.
The best song/prayer leaders add another level of excitement, energy, and connection. I used to see this at camp; both song leaders knew the lyrics and melody, and were technically as proficient. But one always seemed to get the group dancing harder, singing louder, and smiling more than the other. Sadly, this is the hardest part to teach. As Miyamoto Musashi would say, "Practice this diligently."