The analogy of natural vs. prosthetic applies well to pastors and elders in the church. Simply put, when elders come from within the body, they are a natural part of it. This is when the body functions best (see I Corinthians 12:12-31 for more on the church as a body). On the other hand, when a church brings in a pastor from the outside, he and the church function like a prosthetic leg: they work but not nearly as well as a natural leg does.
When elders are recognized from within the body, everyone else already knows them. They shouldn't have to do anything differently than they were already doing before they were recognized. They are a natural part of the church family. One reason the body functions well is because the elders are doing what they should be doing. These elders understand the needs of that particular church body, are trusted by that church body, and can therefore naturally work toward the maturation of that body. When this occurs, the body works well.
Most churches today take the prosthetic route. We all know the general process: when a pastor leaves, the church forms some sort of search committee. They spend numerous hours dutifully going through many resumes. The committee chooses the person who has the best qualifications (years of experience, highest degree, publications, etc.). Essentially, they follow a business model (for example). The church eventually asks a pastor to come shepherd them even though they do not know him.
After the pastor arrives, he has to spend years (literally) getting to know the people to gain their trust. Although he is part of the body, he is not a natural part of the body. After years of getting to know the folks, he will be more like a natural part, but will never achieve this status for one simple reason: he's being paid a salary. He can never be a natural part of the church family like everyone else is.
Churches must make a conscious decision whether they want to walk naturally or with a limp. The natural walk requires elders from the inside. The prosthetic limp is a result of pastors from the outside.
Why would any church want to limp?