As they both mention in this debate, higher criticism of the Bible and other scriptures is already a "mainstream" thing and their theories/conclusions are easily accessible to the layman. This is not yet the case for Islam.
Higher criticism of Islam has existed for a long time, but it is insignificant when compared to the amount of critical scholarship devoted to Judaism and Christianity, and their conclusions are rarely discussed outside of scholarly circles.
This is in part due to the fear produced by Muslim intolerance, a fear which "moderate" Muslims reap the benefit of. For example, Bart Ehrman is an agnostic scholar which Muslims love to use in order to attack Christianity. When asked if he would consider subjecting the Qur'an to such study, he replied, "When I stop valuing my life, that is what I'll do." In fact, Wood, Spencer and Pamella Gellar have just received some more very public death-threats. The Muslim is so emboldened by the West's special treatment of Islam, he doesn't bother hiding his home address (who wants to bet the police don't give a damn?)
Muslims are often very hypocritical, in that they gratuitously accept this higher criticism of other religions, claim that their scriptures have been distorted, etc., but refuse to accept the same about their own religion. Basically saying, "This is what we believe, and if scholars say it is false, we don't care". As Wood and Spencer also point out, even the Islamic texts themselves refute the myth of "One Qur'an, perfectly preserved".
From Jihad Watch:
This much-anticipated debate took place Monday, May 28, at 8PM on ABN. Recently David and I teamed up against Anjem Choudary and Sheikh Omar Bakri to debate the same question, did Muhammad exist? (Watch that one here.) As David explained before our Monday debate, "we showed that two Muslim apologists couldn't defend the existence of their prophet....Choudary and Bakri relied on a backwards, archaic, absurd methodology ('The Qur'an says it, so it must be true!'). Can a more sophisticated argument show that Muhammad existed? Only one way to find out."
Indeed. Watch and see.
And get the book Did Muhammad Exist? here.