Maharal (Tiferes Yisroel #69): It is not proper that the words of the Torah, which are words of wisdom, should be in the hands of fools so that each person can think they are just as competent as anyone else to say what is in the Torah. I discussed this in my sefer Be’er HaGolah. I explained that our sages have deliberately concealed their words in many places in order that fools should not have ready access to them. Therefore if the Torah had been written clearly and explicitly – it would be difficult to distinguish who is truly wise from one who is lacking in wisdom. As a consequence it would produce great disputes. This is the opposite of the intent of the Torah that everything in it should make connection, order and unity in creation. It is in order to prevent dispute and schisms that the Torah says that a rebelious elder is deserving of capital punishment (Sanhedrin 88a). Therefore it is proper that the Torah be in the hands of the few in order that they be listened to. This would prevent the many disputes that we have our day in which everyone imagines that they are a scholar and outstanding religious authority. They believe this because they say, “I can also read seforim.” This causes a number of bad thing which I don’t want to write about. Therefore the Torah is written in a manner that only the elite will comprehend it and so it will be inaccessible to the masses. This universal access to Torah was the cause that the Sanhedrin was not utilized and everyone built a private sanctuary for himself and there was no connection or unity. Thus Devarim (17:11) commands us that when there is a difficult matter it should be dealt with by the Sanhedrin. Thus we see that not writing down the Oral Torah and that it be given to the Sages (rather than the masses) is something inherently necessary for our wellbeing.