By this kind of reasoning, it’s arrogant for me to say that I know my own name, because my parents told me what it was. Perfect strangers who were born twenty years after me – they have much more right to tell me my name than the parents who gave me both life and my name.
If you believe that Jesus Christ became man to save us, and to be the Way, the Truth, and the Life, and if you believe that He wasn’t a big fat liar and did not leave us orphaned of help, then obviously He wasn’t going to set up a situation where the fullness of truth would be hidden from us until Bob the Preacher or Annie the Super-theologian could tell us about it in the year 2015. And indeed, Jesus says that one of the main things that the Holy Spirit will do is to remind us of what Jesus already said and did.
If you believe that God is basically in the business of becoming a human and dying and rising, just in order to leave us as clueless as before He came, then obviously you wouldn’t be interested in anything chronologically close to the source.
(Although if you are interested in the development of doctrine, then Bob and Annie do have a part to play, and hopefully the Holy Spirit is helping 'em out with thinking as well as remembering.)