Seth Godin verbalizes the tension that is always constant in the church. Check out his blog post here.
I see this most in church plants that start out to "do church differently." They do church differently, but then get stuck in doing church the way they have always done church. They stop innovating and growing. They stop pushing forward.
It is easy to see this in action. The Roman Catholic church innovated their liturgy to accomodate the influx of influencial Roman elite that followed Constantine into the Church (they had to be respectable). The Lutheran and Reformed churches solidified their era, as did Anglican, Wesleyan, Pentecostals, and everyone else. Churches from the '80's that wanted to be "contemporary" are now only contemporary if you were in the 1980's.
These are needed, but so too are the innovators.