Parallel Construction

I was helping a friend edit a letter today. I enjoy editing--it awakens that middle school grammar student in me. Besides, MS Word's spelling and grammar check doesn't necessarily address things like commas and parallel construction.
 
Parallel construction? In a letter? Though the actual term eluded me when I was doing the editing, I couldn't help but propose making the items in a list of things have the same grammatical structure. Parallel construction. (Yes, I know I play fast and loose with grammar in this blog. And yes, I know two nouns don't make a sentence. And that you shouldn't start a sentence with "and.")
 
So, aside from following rules in a grammar book written decades ago, why does parallel construction matter? I would argue that it lets the reader know what to expect, and then fulfills the expectation.
 
Knowing what to expect is often what gets us from one point to the next in our days, our weeks, and our lives. It is what makes us feel safe in the face of things unknown. It gives us a bit of a road map for how to react. It serves as a "home base" of sorts when we feel as if we are running in lines that are definitely not straight. It allows us to compare apples to apples when we often seem faced with grapefruits and papayas.
 
I am hopeful that my venture into parallel construction was helpful in the editing job I did for my friend. For me, it was a reminder that a few rules and patterns can be a pretty good thing, especially when so many things in life can be, well, a little unexpected.