As far as the kingdom part of it goes, that is a big part. I do see haughtiness as an issue- a lot of leaders take themselves too seriously. Not that leaders should be casual in what they do, but they don't walk on water, either.
There are also leadership factors that have to be dealt with. There are a lot of worship leaders who don't have leadership skills. It's not an issue of pride or heart, it's an issue of leadership ability. That is just as important as musical ability. I have encountered my fair share of leaders with the right heart and musical talent, but couldn't lead. They had no organization, no direction, no vision, no communication skills, but they can play an instrument and sing, so they are the leader.
It's been said that Martin Luther quipped, "I'd rather be ruled by a competent Turk than an incompetent Christian".
As a bass player and band contributor, I'd rather be led by a secular band leader that can lead than a 'spirit filled' worship leader that has no vision, organization, or direction.