This seems a little peculiar. As if the Almighty had only so much inerrancy to go around, and so saved it for the really important bits.
Let's not forget that we don't even have a single, consistent version of the text to play with in the first place.
According to Bart Ehrman in his book, "Misquoting Jesus," there are more "errors" (meaning differences between various versions of the texts, including mistranslation errors, errors due to illegible writing, and even sections added or removed) in the New Testament than there are words, simply because we have that many competing versions of the texts.
And we aren't talking about minor changes. There are major differences in the texts that significantly change the whole. Remember Jesus stopping a stoning by saying "let him who is without sin cast the first stone?" That little story isn't present in the earliest versions of the text - it was added much later. Clearly this couldn't be a translational issue or other mistake - you don;t have entire stories added to a text by mistranslating a word or two.
How could the Bible possibly be inerrant if the errors and mistakes and mistranslations and additions and subtractions are so blatantly obvious? Which copy of Matthew is inerrant? of Luke?
The most parsimonious answer is of course that none of it is inerrant. That all of it is no more or less accurate than most other religious texts, written by purely human beings, perhaps inspired by their faith but not guided by some omnipotent deity.