In 1803 Luke Howard published an article that gave the classification system and Latin names to clouds We still use his system and his names for clouds. Why is this important? As his biographer later wrote: "Clouds were no longer exempt from human comprehension, in contributing both a system of analysis and a full Latin nomenclature covering their families and genera, had contributed more than anyone to easing the path of understanding...." That alone says the point I am trying to make but to paraphrase a little more In naming clouds he named the unknown.

Through this system we have come to understand the "how" of weather patterns. "Why" is the question that is left not why it works mind you but why it exists?

The same could be said for midichlorians. I have read numerous blogs and engaged in discussions about how many facets of Star Wars are comparable to different religions. Science has always tried to explain the "how" of something to ease understanding of the why of the same phenomena. Many of our scientists today try to discover the hows and whats of history and the universe through Astronomy, radio-carbon dating, oceanography, and etc. For one small purpose to answer the infamous question of Why are we here.

I feel that the idea of adding midichlorians to the mythos did not detract from the force (religion) but rather the midichlorians are a kind of a litmus test to the force(and indeed not definitive of if someone could wield the force but more indicative of to what extent). They are part of the "how" that could answer the "why" one day. In short it is necessary for the star wars universe and the jedi's path to understanding.