I started reading Rob Bell's Velvet Elvis today. I wasn't even 4 pages into the book when Bell stated this point exactly -- except that he doesn't at all attribute it to a difference in personalities.
Here's what often happens: Somebody comes along who has a fresh perspective on the Christian faith. People are inspired. A movement starts. Faith that was stale and dying is now alive. But then the pioneer of the movement -- the painter -- dies and the followers stop exploring. They mistakenly assume that their leader's words were the last ones on the subject, and they freeze their leader's words. They forget that as that innovator was doing this or her part to move things along, that person was merely taking part in the discussion that will go on forever. And so in their commitment to what so-and-so said and did, they end up freezing the faith. -- Rob Bell, in Velvet Elvis
SJ's are the protectors. They value tradition and continuity. They are the ones who remind us how things have been done in the past, who help us remember and adhere to the rules, and who help us to stay on the pathway that we set out upon. It makes sense that they "freeze" the faith at a point because that's the gift/personality that God has bestowed upon them. Without them it would be easy for us to lose focus and wander away from the goals that we set out toward.
NF's are visionaries. Their gift/personality type is one that sees new possibilities, new ways of looking at things, new means of approaching old topics.
NT's are intellectuals. They analyze the ways things have been done and how they might be done better. They innovate and challenge the status quo.
All of these (and SP's as well, of course -- people the Emerging churches are often particularly targeting) are important and valuable perspectives and all are needed to keep a balance. When a church is made up of all SJ's then yes, it will seem very dry and boring and dead. It might not seem dead to the SJ's themselves, but to all of the other personality types that are biding their time in that congregation, it could be quite miserable. But when a church is made up all of NF's, anything goes. You might never know where you'll be from one week to another (theologically, emotionally, etc.) and that might be exciting and refreshing for NF's, but for other personality types, that could be quite unsettling and even disturbing.
God made us with different personality types so that we can learn from each other, so we can balance each other, so that we can guide one another and so that we can love one another despite our differences. We need to learn to listen to each other rather than advocating one personality type over and above another.