I don't think anyone can, at this point, say why the liturgies are taken on certain days (Basil and Chrysostom that is). The texts are readily available for anyone to read from a myriad of sources.
This in a way answers some of my questions. The questions I have about the Liturgy of St. Basil are:
1. Why is it not used as often as the one of St. John C.
2. Why is the Liturgy used on certain days.
It looks like these questions have been for the most part answered by the discussion.
Since I became a Eastern Christian, this has been a curiosity or me, but just never asked it before. I thought I would ask it on this board.