The Bible is a unique book. In addition to being a spiritual revelation, it is also a book that chronicles the history of a particular people: the Israelites. Thus, unlike some (maybe all) other spiritual books, it invites people to review the history as a means of confirming the truth of the Biblical claims. This, in turn, raises two different types of objections. First, some individuals (including archaeologists) require higher scrutiny of the factual claims of the Bible because the more accurate the Bible is historically the more believable it is spiritually. Second, some archaeologists and Biblical doubters simply deny that the accuracy of history in the Bible in any way reflects the truth of the spiritual claims in the Bible.
Side note: in the comments to the Victor Reppert blog entry linked below, one sloppy-thinking atheist reflected this latter view when he commented, "Roswell, New Mexico, is an actual city too. Is this by itself evidence of the existence of aliens?" The poor atheist is confused. He probably intended to ask whether the existence of Roswell is "by itself proof of the existence of aliens." The answer to the question is of course it is not proof of the existence of aliens, but it is evidence for the existence of aliens. Consider: if the City of Roswell, New Mexico did not exist, that would certainly establish that the claims that aliens crash landed there could not be true, wouldn't it? But Roswell does exist (I was there in February) and so the claims that aliens crashed near Roswell can be seen as possible. Thus, while the existence of Roswell doesn't prove that aliens crashed there, the fact that the city of Roswell exists is evidence that supports that assertion. Of course, there are other differences and this argument can get quite a bit more involved, but the point for purposes of this point is that Bible doubters do make this claim.
The two reactions to the Bible's claim to be historically accurate discussed in the first paragraph leads to a rather interesting inconsistency. As correctly discerned in a post by Victor Reppert entitled Archaeological Support for Jeremiah on his great blog, Dangerous Idea,
When evidence is brought forward that supports the accuracy of the text, we are told that this really doesn't matter, since it doesn't support the supernatural content of the text directly. On the other hand, if there is a lack of archaeological support for what the text says, then we are told that this is good reason to reject the text, and especially, to reject the supernatural content of the text.
So, if the Bible is historically accurate the accuracy is irrelevant, but if the Bible is historically inaccurate the inaccuracy is relevant. Thus, under these views the archaeological record is not important as long as it supports the Bible, but when the archaeological record seems contrary to the Bible, atheists and Bible doubters want to jump all over the archaeological record as critical to the Biblical claims.
No offense, but you cannot have it both ways.
Obviously, most people know that Biblical archaeology matters because most people aren't as blinded by their own illogic as these Bible doubters. Most people instinctively recognize that the Bible is a book that claims to be divinely inspired. To those of us of the conservative bent, that leads to the conclusion that it should be historically accurate. Thus, when archaeology turns up evidence that shows that the Bible is based in history, i.e., its historic accounts have a basis in fact that can be backed up with archaeology, then it does add to the legitimacy of the Biblical claims.
Still, and I know this may surprise some people, there are people who don't want Christianity to be true. There are others who will put their presuppositions ahead of the facts and not follow the facts where they lead. And whether you want to believe it or not, some of these people exist in the field of archaeology.
Let me make one thing clear: I am not doubting the bona fides of many in archaeology who openly disclaim the Bible. I am not saying that they are intentionally suppressing archaeological evidence that supports the Bible. However, I do believe that the reporting of the evidence can be colored by one's preconceived notions, and one very strong preconceived notion among some in the field of Biblical archaeology is that the Bible cannot be archaeologically accurate. Thus, when they make broad pronouncements that the Bible is not supported historically, it isn't because they have conclusive evidence that it is unsupportable. Rather, it is because some archaeologists are incapable of seeing past their preconceptions even when the truth is staring them in the face.
The list of Biblical places and people that were thought to not exist but were later proven to exist by archaeology (such as the Pool of Siloam, King David's palace and Pontius Pilate) is long. No, archaeology has not been so kind with some older events (such as the existence of Joseph or the Exodus), but recent findings that archaeologist presently reject or doubt may ultimately be agreed to constitute evidence for these Old Testament things. Given the record of accuracy of those things archaeologists have confirmed, the negative attitude towards the Bible by many in the archaeological field makes me wonder whether the motive is really factual or unwillingness to follow the evidence.