berrygerry, it is not an oral tradition. Rather, it is specific instructions from the Borg that require this kind of intimate questioning.
The reason? Typically, so that elders can know exactly what has happened, in order to be able to give specific help and counsel/discipline.
My opinion is that it has a psychological factor, too: That intimate questioning is a way of exercising power over the 'sheep'. And that is very important. The 'sheep' must know who has power over them, he/she must feel it in their skin, so to speak.
Plus, it feeds the ego of the elders, that kind of exercising power. It sounds twisted, I know, but it's under the greater picture that all of the JC thing is twisted and un-humane in its nature.
This kind of questioning is identical to the Medieval (and later) Inquisition. The only difference is that JCs are not allowed to inflict physical pain and/or death, so they are left with the option of 'spiritual' death (DFing). Thanks to the secular authorities, the Inquisition was banned from carrying death sentences. I think something similar should happen with the JCs. While it would be wrong to expect an authority to completely ban a religion, however banning the carrying out of spiritual death sentences should be something that authorities should look into. I believe that is going to be the case in the next few years.