BUT it seems to me that you are making a majorly flawed assumption: that the teachings found in the Sutta Pitaka have not been "tampered with" over the past 2500 years. That they actually are word for word accounts of the Buddhas teachings. No I am not trying to cast doubts and aspersions over the Sutta Pitaka, but let's look at it somewhat objectively.
This assumption is your conclusion but not what I have said.
What you say can be applied to any teaching, be it in writing or oral.
If one is fortunate to have a teacher who has genuine realization, then what you say is not true, TMingyur. If a teacher is able to teach from the genuine space of primordial wisdom, such teachings are as fresh as were those of Shakyamuni when he actually spoke them 2,500 or so years ago.
AND, what makes you believe that when you read a text that you are not projecting your interpretation onto the text you are reading?
What makes you believe that when you are listening to an oral teaching that you are not projecting your interpretation onto the sounds you are hearing?
The thing about receiving oral teachings is that one can ask the teacher questions and have a dialog to determine if one's understanding is correct.
Have you ever been given an oral explanation of a text? If you have then you will be well aware of the depth of meaning that can exist even in the simplest four line stanza of verse!
The assumption that an alleged "depth of meaning" of a text to arise in one's mind is necessarily dependent on the explanation orally given by another would be ill-founded since the text qua text
that is before one's eyes is actually meaningless symbols and the sounds qua sounds
that one hears actually meaningless sounds.
It is exactly because there is no inherent meaning in the symbols of a written text that one may very well require the explanation of another - who possesses much deeper knowledge of the meaning the text is intended to convey - in order for one to come to such an understanding of it. A single line of teaching may have multiple levels of meaning, but where in the symbols themselves, individually or in their arrangement together, is there a cause for one to be able to discern more than just their face value? On the other hand, while spoken words are just sounds with no inherent meaning, the teacher can explain the meaning as elaborately as needed, even rephrasing or asking probing questions to lead one to encounter the meaning for oneself, until one has been able to come to a proper understanding. Books cannot do that.
But it is not that I would want to assert that there cannot be circumstances where oral explanations can be helpful ...
Heh, I think this kind of goes without saying, my friend.