Good morning;
As I would tell my students, "what you are about to read is a convenient explanation that happens to fit the facts".
While I was shooting this morning, I got to thinking about the reasons for using left or right wing feathers, and the fact that left wing is more traditional. It's the whole superstition of not having an arrow rotate towards the (right handed; this will be important later) archer, so left wing feathers were used.
I think that while that might be part of the answer, the basis of using predominantly left wing feathers is more practical, money.
The archer was the long range and precision battlefield weapon up until about 1800 (more or less). In the same period of history, those that were literate and could write favored right wing quills, because they curve away from the eye of a right-handed writer. So, they were prized, and hence more expensive (and also the basis for referring to a political party as being either "left or right wing", but that is a post for someplace else). Left wing feathers were cheap, since only people of poor standing would use them to write with (and risk getting poked in the eye).
So, if you are a fletcher, and trying to make a little profit supplying the army with arrows, using the cheaper and less desirable left wing feathers is a good way to increase profit margin.
Just a thought.
D