N.T. Wright once wrote in an essay on the methodology of The Jesus Seminar that "hatred of orthodoxy is just as much an unhistorical starting point as love of it". Which I thought was an insightful comment. Wright's essay intended to show that anti-fundamentalism can become its own brand of fundamentalism. It's easy to see how that can happen. If you define yourself in opposition to some person, group or idea then you're really defining your own position via that entity, and we do see examples of this reactionary brand of fundamentalism in various spheres of life, not just in the historical investigation of Jesus. People defining their own political beliefs on the basis of opposing anything done or thought by some political party or figure, for example. Or Richard Dawkins, for another example (hopefully that doesn't need clarification).
There is at least one more brand of fundamentalism that is even more subtle than this 'reactionary fundamentalism'. This third brand of fundamentalism defines itself via the following central dogma: the precise center of any two extreme positions on any issue is the correct position. Something we might call 'Methodological Moderation'.
Of course no one knowingly or admittedly thinks like this, just like no one in the Jesus seminar proudly declares their fundamentalist anti-fundamentalism. Nevertheless this methodology for arriving at positions on issues is something that some people do, for whatever reason.
You see it in the political sphere with moderates who wear their "independent" party affiliation as a badge of honor and denounce any extremism from any corner on any issue whenever they get the chance. Always making sure to communicate their unwavering centrality, and the evil of extremes. And although this fundamentalism may often appear thoughtful, it's just as dogmatic and unthinking as someone who blindly toes a particular party line.
You see it in the personal realm with certain personality types. The types of people who refuse to take sides in an argument, or always try to see everything from 'both perspectives'--even in the cases where one perspective is clearly in the wrong and should be accorded no weight.
Returning to N.T. Wright, you also see it in the realm of theology. I don't think Wright is always guilty of it--he affirms certain extremes as he should--though I think he lapses into it at times. Anglicanism is famously defined as a middle-way between Catholic Orthodoxy and Protestantism, but Wright often seems to be obsessively looking for 'middle ways' on a wide array of issues as a matter of method; the historical Jesus, eschatalogical issues, the Old and New Perspective on Paul, etc. That doesn't mean he's always wrong to do so, but excessively searching for middles and compromises has associated dangers.
Of course sometimes looking for the 'middle way' can bear significant fruit, and sometimes the moderate middle really is the best place to be. But other times this method can replace a search for truth with a search for the middle. The problem with that is that truth often is found in extremes.
Many of us have used the aphorism "In all things moderation", and there is a certain kind of whimsical wisdom there. However, if we attempt to turn this aphorism into a methodology--as the dogmatic political or theological centrist does--we quickly see that the apparent wisdom of the phrase is lacking. In giving to the poor, moderation? In preaching the Gospel, moderation? In praising God, moderation? In fighting evil, moderation? In prayer, moderation? In opposing injustice, moderation? Some things should be done--or believed--to the utmost extreme. And some things should be opposed vigorously and ceaselessly.
Even when the truth itself isn't necessarily found at a particular extreme, exploring extremes can be more helpful at teasing out truth than trolling the middle. When you take certain beliefs or strains of thought to their reductio ad absurdum--their extreme logical conclusion--this will often tell you what you need to know about the beliefs themselves, even in their non-extreme form.
Extremism has its pitfalls but so does extreme anti-extremism.