C.S. LEWIS once said something to the effect that no Christian doctrine ever looked so threadbare to him as when he had just finished successfully defending it. The reason is not hard to find.
In order to defend the faith successfully—which is the business of apologists—they need to reduce it to a defendable size. It is easier to hold a fortress against the enemy than to hold a landscape. They try to make each doctrine as it comes along sound as logical and plausible as they can. The trouble, of course, is that by and large logic and plausibility are not the heart of the matter, and therefore apologists are apt to end up proclaiming a faith that may be quite persuasive on paper, but is difficult to imagine either them or anyone else getting very excited about.
The other danger is that apologists put so much effort into what they do that they may end up not so much defending the faith because they believe it is true as believing the faith is true because they have worked so hard and long to defend it.